Integrated Photonics Platforms IV

Climate change is one of the greatest and most urgent challenges of our time. If we want to keep the planet livable, greenhouse gas emissions must be net zero by 2050. Food production is responsible for up to a staggering 34% of greenhouse gas emissions. At the same time, our food production is highly sensitive to climate change and this is already having a major impact on the food system, such as crop failures due to extreme weather conditions. As a result, food security and food sustainability are top of mind. Technology can and will make the difference. The unprecedented convergence of AI, gene editing, DNA synthesis and biotechnology will revolutionize global industry, particularly in the agrifood domain. This presentation will show how optical sensing in general and photonic integrated circuits in particular are unique and indispensable technologies that provide solutions for farmers, food processing industry and consumers, and will help guide the transition of our food ecosystem to a more secure and sustainable industry. New tools in barns, in greenhouses, in orchards, in protein bioreactors and the accompanying digital twin AI technology will be shown.

Spectral imaging has long promised to uncover physiological and molecular information invisible to the human eye. Yet, despite decades of innovation, its translation into clinical routine has been slow. Beyond regulatory hurdles, challenges such as ill-posed inverse problems, data scarcity, and the demand for real-time analysis have repeatedly stalled progress. In this keynote, I will present recent breakthroughs at the intersection of computational biophotonics and machine learning that are reshaping the field. I will discuss how we combine spectral imaging with deep learning to achieve real-time tissue characterization in surgery and intensive care. Case studies will illustrate how spectral imaging can enable context-sensitive, clinically actionable support during interventions, transforming invisible spectral signatures into robust biomarkers. I will highlight not only our successes but also the failures that have shaped them. From spectral unmixing approaches that collapsed under distribution shifts to algorithms that failed spectacularly in the operating room, I will show how negative results became the foundation for new strategies. By dissecting what went wrong, we discovered how to adapt models across species and sensors, quantify uncertainty in predictions, and build validation frameworks that hold up under clinical reality. By putting the spotlight on failure—and how it fuels methodological innovation—I will argue that embracing negative results is the key to moving spectral imaging, powered by AI, from promise to practice. The future of the field may not depend on avoiding failure, but on failing better.

As photonic integration advances toward scalable, high-throughput manufacturing, the integration of active devices-particularly lasers- remains a key challenge. Vanguard Automation addresses this with a unique solution of photonic wire bonds and facet-attached micro-lenses, which are fabricated in-situ at chip-level and can be applied to both batch processing and wafer level integration. This solution leverages 3D nano-printing technology to fabricate freeform optical structures with sub-micron precision which eliminate the need for active alignment, while enabling robust, low-loss, high-yield photonic interconnects. Vanguard Automation’s solution is uniquely positioned to meet industry demands, lighting the way for scalable next-generation photonic integration.

A versatile packaging concept using collimated out-of-plane beams as a common optical interface between components like photonic integrated circuits, laser diodes (LDs), polymer waveguides and optical fibers is presented. Therefore, each component is integrated on a substrate together with micro-optical elements such as mirrors and lenses, which emit/receive collimated expanded beams out-of-plane, enabling low-loss, alignment-tolerant coupling. Two C-band configurations demonstrate the approach: (1) coupling a single-mode fiber (SMF) to a collimated circular beam out-of-plane with a mode field diameter of 40μm using an off-axis parabolic (OAP) mirror, and (2) coupling the elliptical beam emitted by an indium phosphide LD to the same out-of-plane 40μm beam using an OAP mirror. The micro-optics have been fabricated using two-photon polymerization and validated through characterization.

Heterogeneous integration is the main path forward for advanced integrated photonics, but expanding functionality with new materials often requires complex process modifications. While III-V and TFLN platforms have enabled laser sources and electro-optic switches, extending these approaches to frequency combs and quantum applications increases fabrication challenges. Polymer host-guest systems offer an alternative, separating fabrication and functionality: the polymer host defines the process, while organic dyes provide optical properties. A wide range of dyes supports lasers, modulators, Kerr combs, and single-photon sources without altering the base fabrication process. This work presents a framework for an active polymer photonic platform, studying the nonlinear, lasing, and quantum properties of organic dyes with Kerr coefficients of 10⁻¹⁵ - 10⁻¹⁶ m²/W. Fabrication employs direct laser writing for UV-stable dyes and inkjet printing for localized elements in pre-formed trenches. Demonstrated structures - waveguides, ring resonators, and couplers - highlight the potential for scalable polymer-based heterogeneous photonic integration.

We demonstrate hybrid integrated GaN laser diodes (LDs) at 488 nm on the SiN photonic platform using flip-chip bonding. Fork-shaped edge couplers were designed and fabricated to reach a coupling loss of -2.2 dB with LDs at the optimal alignment position. Pedestal structures with sub-50 nm height variation were completed through a two-step lithography process to enable precise vertical alignment. The LDs were picked up and accurately placed on the pedestals in flip-chip bonding, achieving a total coupling loss of ~9 dB and an average in-waveguide optical power of 0.2 mW driven by a pulse current of 400 mA with a 5% duty cycle. This work paves the way towards photonic systems integrated with visible lasers for life science and quantum applications.

Micro transfer printing (µTP) is a key technology for heterogeneous integration, enabling precise placement of devices on various substrates. It combines materials with different processing needs, achieving high accuracy and scalability. The presentation covers µTP principles, factors affecting yield and reliability, and highlights Tyndall National Institute’s recent advancements in III-V integration and photonic device assembly, emphasising its support for the Europractice wafer services for the research and industrial community.

This study presents the technological development carried out for the heterogeneous integration of Gallium-Antimonide (GaSb) based optoelectronic devices on Silicon-Germanium (SiGe) photonic circuit through the Micro-Transfer Printing (µTP) technique.

Heterogeneous integration of lithium niobate (LN) onto silicon nitride (SiN) enables compact electro-optic tuning by combining LN its strong Pockels effect with CMOS-compatible low-loss SiN photonics. Building on earlier demonstrations of LN-on-SiN all-pass modulators, we demonstrate micro-transfer printed racetrack-shaped LN slabs of 250 nm and 200 nm thickness onto add–drop SiN racetrack resonators to achieve tunable filtering and switching at 1550 nm and 1310 nm. By varying the bus–resonator gap from 510 nm to 710 nm, critical coupling is obtained, with passive measurements showing 30 dB extinction, a 940 pm FSR, and a 20 pm FWHM at C-band.

Direct epitaxial growth of III–V quantum-dot (QD) gain media on silicon offers a promising route toward wafer-scale, monolithically integrated light sources, though performance is often limited by defect-related thermal sensitivity. Building on a low-defect III–V-on-Si platform, we demonstrate Fabry–Perot lasers emitting at 1.3 μm, focusing on scalable fabrication and temperature-dependent performance. Broad-area devices exhibit a low CW threshold current density of 54 A cm⁻² and operate up to 125 °C. Narrow ridge lasers achieve thresholds as low as 6 mA (RT) and 12 mA (80 °C), with operation up to 165 °C and high output power. Comparable performance to GaAs-based devices highlights the effectiveness of the approach for integrated silicon photonics.

Aluminum oxide (Al2O3) is a versatile integrated photonics platform due to its low optical loss and broad transparency from the ultraviolet to the infrared, enabling the integration of both active and passive photonic components. In this invited talk, we focus on rare-earth-doped Al2O3 integrated waveguide amplifiers developed using reactive co-sputtering. The platform supports efficient incorporation of multiple rare-earth dopants, including Er, Tm, Nd, and Yb, allowing on-chip amplification across different wavelength bands. We present an overview of recent progress in amplifier performance, optical gain, emission properties, and lifetime measurements. The results illustrate the potential of Al2O3 as a multifunctional and scalable platform for integrated photonic systems.

We report on the telecom-band implementation of a substrate-transferred Ba0.8Sr0.2TiO3 (BST)-based electro-optically tunable Fabry-Pérot band-pass filter and investigate the influence of electrodes solely on the top surface of the electro-optic layer versus lateral electrode configurations on the electric-field distribution within the active layer. Numerical simulations show that lateral electrodes increase the effective bias-field strength within the BST film by approximately 28%, as quantified by the average surface-integrated squared electric field over the optically active BST area. These results suggest that lateral electrodes can improve the electro-optic actuation efficiency of BST-based tunable filters in the telecom range.

The LOLIPOP project leverages thin film lithium niobate on insulator (LNOI) and semiconductors to produce active elements and explores hybrid integration techniques to enhance silicon nitride (SiN) photonic platform. The TriPleX circuits aim to deliver ultra-wideband (400–1600 nm) high-performance PICs. Key technologies include micro-transfer printing (μTP) of LNOI, GaAs flip-chip bonding, and edge coupling. Demonstrators cover LDV (leveraging second harmonic generation), LiDAR, neuromorphic processors (10–40 Gbaud at 1550 nm), and squeezed-state engines (6 dB squeezing at 1560 nm, ECL at 780 nm). Finally, novel Germanium broadband photodiodes integrated into SiN. The presentation addresses challenges and outlines design, development and packaging advancements

A versatile photonic integrated circuit platform capable of operating across a broad spectral range - from ultraviolet to infrared - is vital for the advancement of on-chip optical microscopy, spectroscopy, and emerging quantum technologies. Such a platform should offer low propagation loss, minimal autofluorescence background, and a high refractive index contrast to enable compact, high-performance designs. In this work, we present Al2O3 waveguide platform fabricated using atomic layer deposition that meets these key criteria. At wavelengths of 375 nm and 405 nm, the Al2O3 strip waveguide exhibits low propagation loss below 0.75 dB/cm and 0.50 dB/cm, respectively, together with exceptionally low autofluorescence compared to conventional Si3N4 and Ta2O5 waveguides. These features make the Al2O3 platform a highly promising candidate for next-generation, ultra-sensitive on-chip bioimaging, spectroscopy, and trapped-ion quantum computing applications.

The integration of other materials on SiN enables new functionalities such as lasing, modulation and detection. Ligentec works on integrating all these functionalities on its low loss integrated photonics platform through heterogeneous integration. Through wafer-bonding, lithium-niobate and lithium-tantalate high-speed and low-insertion loss modulators are fabricated on a mature silicon nitride technology platform. We show a path towards scaling this approach for volume fabrication. Furthermore, we highlight device innovations that can increase bandwidth and lower drive voltage.

Photonic neural networks (PNNs) enable ultrafast and broadband computation using the intrinsic properties of light, but conventional matrix–vector multiplication (MVM) schemes suffer from lossy coupling and off-chip nonlinearities, limiting efficiency and scalability. We present a monolithic approach integrating passive nonlinear activation and linear electro-optic operations on a thin-film lithium niobate (TFLN) platform. Periodically poled TFLN (PPLN) waveguides provide nonlinear activation via second-harmonic generation, while low-voltage electro-optic modulators (EOMs) enable high-speed control. Efficient fiber-to-chip coupling is achieved using direct laser-written polymer lenses with low loss and broadband performance. This co-integrated architecture offers a compact, energy-efficient, and scalable foundation for next-generation photonic neural networks.

We demonstrate ultra–low-noise photonic integrated self-injection–locked lasers with fast, efficient frequency tuning enabled by monolithically integrated piezoelectric actuators. The actuator design maximizes stress overlap with the optical waveguide, ensuring strong and uniform refractive index modulation at low voltages. Guided by finite element modeling, the optimized geometry concentrates mechanical deformation where it most effectively alters the optical mode. The lasers are fabricated on ultra–low-loss Si₃N₄ photonic integrated circuits incorporating aluminum scandium nitride (AlScN) actuators, which provide a threefold increase in actuation efficiency compared to AlN and enable nearly an order-of-magnitude improvement in tuning performance. The devices exhibit linear, wideband tuning across multiple laser drive currents and continuous frequency chirps exceeding the resonator free spectral range, demonstrating seamless mode-hop–free operation. This scalable, co-designed platform enables high-speed, low-power, and broadband tunable lasers for next-generation applications in optical communications, spectroscopy, and FMCW LiDAR.

We report the development of the first monolithic electro-optic modulator based on sol-gel barium titanate (BTO). The material is synthesized by chemical solution deposition and patterned using soft nanoimprint lithography (SNIL), enabling a scalable bottom-up fabrication compatible with silicon dioxide substrates. Optical mode confinement at 1550 nm is achieved thanks to the relatively high refractive index of sol-gel BTO (~1.85). We characterize the optical losses and electro-optic response (VπL) of the fabricated waveguides, demonstrating that reducing the final annealing temperature from 800 °C to 700 °C enhances the modulation efficiency by 1.5 times and reduces optical losses by 50%. These results highlight the tunability of the device performance as a function of sol-gel BTO properties and their potential for scalable integration in photonic circuits.

I will review our recent work on optical phased arrays in silicon nitride technology and their hybrid integration with extended cavity lasers. Our application fields cover light sheet microscopy, flow cytometry and ophthalmology.

Laser Doppler vibrometers (LDVs) measure surface vibrations using the Doppler shift of reflected light and can be integrated into photonic integrated circuits (PICs). Multibeam LDV PICs enable simultaneous sensing at many points, but scaling to high channel counts is limited by the large number of electrical pads required. These pads consume chip area, complicate routing, and increase cost. We introduce a flip chip packaging approach to overcome this challenge. The LDV beams exit from the polished backside of the PIC, while the topside uses a ball grid array for electrical connections. A glass interposer redistributes the dense pads to larger external interfaces. This design improves integration density and manufacturability. We demonstrate a device with 16 beams and 60 pads, enabling low crosstalk, multi point vibration measurements.

We present thin-film lithium niobate integrated photonic circuits specifically engineered for the on-chip generation and detection of broadband terahertz pulses. By exploiting the exceptionally large second-order nonlinear response of lithium niobate at millimeter-wave and terahertz frequencies, together with its low optical propagation losses, we demonstrate hybrid integrated architectures that seamlessly combine planar antennas and transmission lines for terahertz radiation with optical waveguides for efficient optical beam delivery and manipulation. The tight co-design of metallic terahertz structures and guided optical modes enables phase-matching conditions that are fundamentally inaccessible in bulk lithium niobate, thereby enhancing optical–terahertz interaction efficiency. Beyond spectroscopy and ultrafast signal processing, this integrated platform provides a promising technological launchpad for future photonic terahertz transceivers targeting emerging short-range THz communication and 6G systems

We demonstrate tunable, narrowband photonics filtering for THz signals, providing optical gain by leveraging regenerative amplification of an optical injected signal into a custom-designed on-chip feedback-controlled multi-wavelength laser. By tuning the feedback phase, the filter response can be dynamically controlled. Experimentally, we demonstrate selective filtering of THz-upconverted signals with 160 MHz bandwidth, 20 dB suppression ratio, and 15 dB optical gain, offering a compact solution for next-generation THz communication systems.

Photonic Integrated Circuits (PICs) operating in the mid-IR are rapidly developing. The goal is to fill the technological gap with respect to the very well developed visible and near-IR PICs, in view of applications. We present recent developments on low-loss passive waveguides and high-quality factor (Q) resonators ans integrated modulators on InGaAs/InP platform for operation in the two mid-IR atmospheric transparency windows (3-5 µm and 8-12 µm).

We present a high efficiency edge coupler on a suspended Si platform for mid-infrared (MIR) operation at 3.3 μm. The device enables compact footprint and efficient free-space-to-chip coupling by integrating Y-junction-like structure with anti-reflection gratings at the input facet. Experimental results demonstrate a coupling efficiency of -1.93dB per edge coupler. This work provides a promising approach for compact and efficient MIR coupling in integrated photonics platform.

This paper presents the development of a hybrid platform combining the outstanding mid-IR emission properties of rare earth-doped chalcogenides materials with the degrees of freedom and electro-optic functionalities offered by the Si photonics platform. Successful Dy3+-doped Ga5Ge20Sb10Se65 RF magnetron sputtering on Si strip and suspended Si subwavelength structures is first demonstrated. Broadband mid-IR emission up to 5 µm is then reported from these hybrid integrated rare earth-doped chalcogenides/Si structures.

Laser coupling is a key point to be optimized for the development of practical devices based on SiGe photonic circuits in the mid-IR. Direct edge coupling between quantum cascade lasers (QCL) and SiGe-based waveguides is a simple and effective approach to implement, but suffers from reflection contributing to coupling losses. In this work, it will be shown that using subwavelength grating-structured facets it is possible to reduce the facet reflectivity down to 6% with an average 3 dB transmission gain in TM mode and 1 dB transmission gain in TE mode at 8 µm wavelength.

In this work, we present and discuss new results obtained during the development of the MIRPIC photonic integration platform, designed for the mid-infrared spectral range. The platform combines germanium-on-silicon (Ge-on-Si) technology for passive waveguiding circuits with active components, such as quantum and interband cascade lasers (QCLs and ICLs), as well as antimonide-based superlattice detectors, optimized for integration with the passive circuits. The platform’s potential will be illustrated using the first technology demonstrators targeting free-space communication and sensing. Additionally, the major challenges will be discussed from the perspective of scaling up and industrialization potential. Acknowledgments: This work received support from the National Center for Research and Development through projects MIRPIC (TECHMATSTRATEG-III/0026/2019-00), HyperPIC (FENG.02.10-IP.01-0005/23, IPCEI ME/CT) and FSOC (FENG.01.01-IP.01-A0MR/24-00), and from the EU Horizon Europe under GA #101213727, Chips Joint Undertaking.

Germanium-on-Silicon (GoS) waveguides are of growing interest for environmental monitoring and chemical sensing due to their wide transparency window (2–15 µm) and potential for low optical loss. These waveguides are particularly suited for on-chip mid-IR spectroscopy. Air-cladded GoS waveguides have achieved losses as low as 0.6 dB/cm but would only be practical for many real-world applications if a top cladding is used to isolate the optical mode from the chip environment. Amorphous silicon (a-Si) is CMOS-compatible and therefore an attractive cladding material. In this work, we present an a-Si-cladded GoS waveguide with a propagation loss of 4 dB/cm at a wavelength of 6 µm.

Quantum-enhanced imaging is an emerging area of research with relevance to a wide variety of application areas, including transport, gaming, environmental research, and security and defence. This subject encompasses a range of techniques and utilizes a number of developing quantum technologies. Time-resolved single-photon imaging approaches have been used to reconstruct high-resolution three-dimensional images, including challenging scenarios such as imaging through atmospheric obscurants and clutter. Critically, this approach has been extended to imaging in turbid underwater conditions. In the past, image reconstruction often proved to be time-consuming due to the inherent computational complexity, however advances in algorithms and hardware have allowed examples of “real-time” reconstruction of moving targets. Single-photon imaging has been used in demonstrations of moving target identification and human activity recognition with the aid of artificial intelligence approaches. Alternative single-photon imaging approaches, such as ghost imaging, will also be discussed.

I will present the PIXEurope Pilot Line, a recently started 400MEuro initiative under the Chips JU, that aims at developing and transferring advanced photonic integrated circuit (PIC) technologies and processes. Through Open Access, PIXEurope will support end-users in increasing the readiness level of their products. I will also present some technologies, leveraging PICs, that were developed at ICFO and transferred to spin-offs, now commercializing quantum random number generators, cryptography systems and phase imagers. Biography: Valerio Pruneri is an ICREA Professor and Corning Inc. chair, leading the Optoelectronics group at ICFO. He is also the Director of PIXEurope Pilot Line. Previously he worked for Avanex, Corning, Pirelli, and the University of Southampton. With his groups in academia and industry, he has developed technologies for the photonic, photonic integration, and quantum. He is inventor in more than 70 granted or pending patent families, leading to numerous industrial collaborations and the creation of four spin offs, Quside, Sixsenso, Luxquanta and Shinephi.

To address the persistent challenges of mode mismatch and alignment sensitivity in thin film lithium niobate (TFLN) photonic integration, a novel fiber-to-chip edge coupling method based on an all-dielectric double-layer metasurface (DLMS) is proposed and theoretically investigated. The DLMS structure, inspired by the optical functionality of two orthogonal cylindrical lenses, is designed to reshape a Gaussian beam emitted from an optical fiber into an elliptical profile closely matched to the guided mode of rib-type TFLN waveguides. A coupling loss (CL) below 1.9 dB/facet across the full telecommunication band (1460–1630 nm) is achieved, with a minimum CL of 0.6 dB/facet at 1550 nm.

Silicon photonics (Si-Pho) is experiencing rapid advancements driven by demands for high-speed, low-power optical communication in data centers and emerging AI applications. Here, cavities as unique photonics features were designed to be in two modules; the first one is under the Metal heater to reduce heat loss, and the other is under the Edge coupler to enhance optical propagation. This application requires us to ensure the cavity is residue-free for better optical transmission and minimal depth to avoid top structure fracture. We developed extreme lateral etch (width/depth >3) to break this tradeoff by employing Lam internal AI/ML-based internal platform to design splits and optimize process recipes. Bayesian Neural Networks method was used to train model and predict optimized recipes. Prediction verification on Lam tools got desired results and saved 70% cost. These fast and cost-effective results enable us to explore brand new ML solutions on Si-Pho manufacturing.

Energy efficiency is a major challenge for scalable integrated photonic technologies, especially in applications such as electro-optical modulators, frequency combs, and all-optical interconnects. Organic materials offer a promising route toward low-energy photonics due to their high nonlinear optical (NLO) efficiency, tunable properties, and cost-effective wet-coating fabrication. A critical step is integrating low-loss passive waveguides with active host-guest structures on the same chip. We present a two-step lithography process enabling such integration. The process begins with Cu alignment markers on SiO₂, followed by SU-8 passive waveguide fabrication and a second lithography step defining active SU-8/dye resonant elements. Devices consisting of edge couplers, waveguides, and ring resonators were fabricated and characterized for optical losses and Q-factors. This approach demonstrates a pathway toward fully organic, energy-efficient photonic components such as frequency combs and other all-optical devices.

When combining different laser sources in a polarization-maintaining fibre, only certain spectral ranges can be coupled with minimal loss. In particular, coupling different laser sources in a polarisation-maintaining step-index fibre in the visible and near-infrared (NIR) range results in considerable losses. Furthermore, coupling higher laser powers in highly integrated systems can lead to thermally induced misalignment of the coupling optics, as well as destruction of the fibre end face or the PM fibre used. As part of the investigation, three laser sources were coupled with low loss over a bandwidth of more than 600 nm into an endless single-mode, polarization-maintaining photonic crystal fibre. To achieve this, the fibre was equipped with special customised end caps. Coupling was performed via a highly integrated ceramic optical bench and transfer-coated micro-optics. The surfaces of the manufactured micro-optics and fibre end caps can be cost-effectively coated using the developed broadband transfer coating.

In this work, we present and discuss a new process design kit (PDK) for the mid-infrared photonic integration platform – MIRPIC. It is based on Ge-on-Si technology and covers the spectral range from 3.0 µm to 8.0 µm. The measured propagation loss of passive waveguides, a key figure of merit for any passive photonic platform, is below 2.5 dB/cm. The library of basic and composite building blocks of the developed PDK includes passive waveguides, tapers, bends, multimode interference (MMI) splitters and couplers, arrayed waveguide grating (AWG) wavelength (de)multiplexers, Bragg gratings, and grating couplers. Acknowledgments: This work received support from the National Center for Research and Development through projects MIRPIC (TECHMATSTRATEG-III/0026/2019-00), HyperPIC (FENG.02.10-IP.01-0005/23, IPCEI ME/CT) and FSOC (FENG.01.01-IP.01-A0MR/24-00), and from the EU Horizon Europe under GA #101213727, Chips Joint Undertaking.

We present a CMOS-compatible hybrid III-V-on-Si QD DBR laser design that avoids tapering the III-V ridge to simplify fabrication. Supermode-based simulations on 220-nm SOI show that, by using high-Al claddings to lower the III-V effective index, the fundamental hybrid mode is predominantly confined in III-V in the gain section and then efficiently transferred into the silicon waveguide for feedback and spectral selection. We analyze several design variants and discuss the trade-offs between optical performance, process complexity (including high-Al handling), and cost. The findings indicate a practical design window for taper-free, CMOS-compatible hybrid QD DBR lasers and quantify the requirements for high-Al claddings in each design.

BaTiO3 (BTO) offers strong electro-optic (EO) response for integrated photonics. We grow high-quality BTO on MgO by pulsed-laser deposition without buffer layers and realize amorphous, c-axis, cubic, and a-axis films suitable for rib waveguides. Device-level evaluation uses Mach–Zehnder interferometers: unbalanced arms for free-spectral-range (FSR) analysis and balanced arms for half-wave voltage. Combining measurements with field simulations, we extract reff for each orientation. a-axis devices show Vπ·L = 0.075 V·cm at 1.55 µm and reff ≈ 1263 pm/V (corresponding to r42 ≈ 1785 pm/V). This buffer-free, planar process enables orientation engineering for high-efficiency, scalable EO modulators.

This paper applies design centering to maximize the yield of grating couplers in photonic integrated circuits. 2D finite-difference time-domain simulations and on-chip experiments assess performance. Bayesian optimization, artificial neural networks and residual analysis reduce simulation needs, enabling yield-optimized geometry predictions based on typical foundry process variations. A semi-automated setup accounts for fiber-to-chip measurement uncertainty.

Scalable neutral-atom quantum computing requires precise, stable, and high-speed optical control of large qubit arrays. However, current free-space optical addressing architectures are fundamentally limited in footprint, environmental stability, and parallelization. Photonic integrated circuits (PICs) based on thin-film lithium niobate provide a promising path toward compact, reproducible, and broadband optical modulation at visible wavelengths. In this work, we present the design and optimization of lithium-niobate waveguide structures for efficient light routing around 556 nm, a wavelength central to Ytterbium-Rydberg-based quantum computing platforms. The PIC enables active calibration and on-chip stabilization of the optical power by compensating thermal and electrical drifts significantly improving long-term operational stability. First results support the development of compact, multi-channel optical control modules capable of scaling to hundreds or thousands of individually addressable atomic qubits, and are broadly applicable to quantum computing, quantum networking, and precision photonic sensing systems.

We demonstrate for the first time on-chip stimulated Brillouin scattering in a monolithic tellurite (TeO2) waveguide through numerical simulations. Our simulation results have shown the confinement of the optical and acoustic modes within the waveguide, leading to an enhanced opto-acoustic interaction. As a result, Brillouin gain coefficients of up to ~190 /W/m have been obtained in a rib waveguide on a silica substrate.

We investigate enhanced spontaneous parametric down-conversion (SPDC) in periodically poled thin-film lithium niobate (TFLN) using a pump-only resonant scheme. Unlike doubly resonant approaches, this method simplifies design constraints while maintaining broadband signal and idler extraction. By engineering high-Q ring resonators at the pump wavelength and optimizing directional couplers for critical coupling, we achieve significant intra-cavity power enhancement. Combined with high-fidelity periodic poling exhibiting a near-ideal 50% duty cycle, this approach improves SPDC efficiency and source brightness. The presented platform offers a scalable and fabrication-tolerant route toward compact, low-power quantum photonic sources for integrated applications.

In a non-linear photonic chip, the waveguide parameters, critical for an efficient grating coupler, are often dictated by the non-linear process. These limitations could lead to poor coupling of light on and off the chip. Here we propose a flexible design strategy to achieve efficient coupling and polarisation separation on the same grating coupler while working in such a restricted parameter space.

Micro-transfer printing (uTP) gives the possibility to combine components from different substrates onto one common carrier chip. While its highly parallel manner allows for exceptional throughput, the ability to pre-characterise the components, make it a good die only approach, with high yield. The goal of this work is to combine devices containing waveguide-integrated superconducting nanowire single-photon detectors (SNSPDs) fabricated on ultra low loss SiN photonics to enable quantum computing applications and quantum key distribution.

Ring resonators are among the most fundamental and versatile components of photonic integrated circuits (PICs), with proven applications in sensing, filtering, and wavelength demultiplexing. Despite their simple geometry, based on a waveguide loop coupled to a bus waveguide, ring resonators continue to offer new opportunities for enhancing performance and integrating functionality of optical systems. In this work, we present recent progress in developing silicon nitride (SiN)-based ring resonator structures integrated with metal–insulator–metal (MIM) plasmonic waveguides for refractive index sensing applications, fabricated at the Centre for Advanced Materials and Technologies (CEZAMAT) and the Institute of Microelectronics and Optoelectronics (IMiO), Warsaw University of Technology.

Free-Space Optical Communication (FSOC) is an advanced wireless technology enabling high-speed data transmission without requiring physical fiber-optic infrastructure. Operating in unlicensed spectral bands, FSOC avoids spectrum congestion, offers immunity to electromagnetic interference, and provides high security due to narrow-beam transmission, making eavesdropping highly difficult. Its low latency, high energy efficiency, and rapid deployability make FSOC an attractive solution for last-mile access, temporary or emergency links, satellite communication, and high-capacity terrestrial or air-to-ground channels. These advantages position FSOC as a complementary or alternative technology to fiber systems, especially where cable deployment is impractical or cost-prohibitive. This work aims to combine the strengths of FSOC with the unique capabilities of InP-based photonic integrated circuits (PICs), which enable the compact, robust, and energy-efficient integration of multiple optical functions within a single chip. We present the design, fabrication, and experimental evaluation of multi-channel integrated transceivers developed using a generic InP platform and dedicated to FSOC applications. The transmitter circuits integrate distributed Bragg reflector (DBR) lasers, electro-absorption modulators (EAMs), and arrayed-waveguide gratings (AWGs), while the receiver comprises an array of photodiodes coupled to an AWG. Furthermore, we introduce a new FSOC-dedicated transceiver architecture featuring four wavelength channels and semiconductor optical amplifiers (SOAs) positioned at the AWG outputs to enhance optical power and improve the overall free-space link budget. Comprehensive characterization involved measurements of DBR lasers, modulators, and AWG spectral responses, as well as BER and eye-diagram analyses for single- and multi-channel transmission. Open eye diagrams were recorded at data rates up to 10 Gb/s. For a two-channel FSOC link over a 100 m distance, a received optical power of –17 dBm enabled error-free operation with a BER of 10⁻¹². Transmission experiments were carried out in both indoor and outdoor conditions using the designed integrated transmitter, confirming its robustness and stable performance in practical optical-wireless scenarios. This work was funded under the FENG programme, project “Integrated Photonics Systems for Free-Space Optical Communication (FSOC)”, FENG.01.01-IP.01-A0MR/24-00.

Free-space optical communication (FSOC) enables high-capacity, secure links without fiber infrastructure, operating in unlicensed optical bands. Most FSOC systems use the near-infrared (NIR) range, but extending operation to the mid-infrared (MIR) can reduce scattering and improve performance in adverse conditions. This work presents integrated FSOC solutions across 1.55 µm, 3-5 µm, and 8-12 µm bands. The NIR system uses InP-based transmitters and receivers with DBR lasers, electro-absorption modulators, and AWG multiplexers, achieving 10 Gb/s transmission. The MIR system employs hybrid-integrated, directly modulated quantum cascade lasers on a Ge-on-Si platform, combined via MMI or AWG structures, with integrated detectors supporting up to 1 Gb/s per channel. This research was supported by the National Centre for Research and Development through project FSOC (FENG.01.01-IP.01-A0MR/24-00)

In programmable photonic integrated circuits (PPICs), light routing is achieved by interconnecting waveguides. This results in optical paths that give rise to a mesh structure using interconnection blocks. Photonics mesh networks implement directional couplers as one of their main components, which are then interconnected into different topologies to form optical routing elements. Control techniques based on optoelectronic principles allow the direction of light to be controlled along the desired optical path. These techniques also perform on/off switching, phase tuning, and power balancing between ports. This work presents a horn-slab directional coupler based on hydrogenated amorphous silicon for 1 µm x 1 µm multimode waveguides. This straight coupler drops the S-bends found in traditional directional couplers. The design mitigates the effect of thermal crosstalk by supporting a separation of at least 1 µm between guides using adiabatic "horn" sections that expand the mode toward a lightly etched slab region and then compress it again at the output. Coupled mode theory (CMT) and the Beam Propagation Method (BPM) are used for the analysis. After exploring this new structure, we will propose a 4x4 matrix with two solutions, using the Thermo-Optic Effect (TOE) and the Carrier Depletion Phenomenon (CDP) as control elements. Keywords: programmable photonic integrated circuits; photonics

Silicon carbide (SiC) is a prominent wide bandgap semiconductor for power electronics applications, due to its high breakthrough field strength, high thermal conductivity and low capacity. In recent years SiC has also emerged as a very promising candidate for integrated (quantum) photonics. This is because this wide bandgap material has many strengths, including being a mature technology platform, CMOS and bio-compatible, non-toxic and has unique photonic properties, such as high second-order and third-order nonlinearities, a high refractive index, a low intrinsic optical loss material that can host versatile color centers. However, despite these good material properties, three substantial challenges have to be addressed: a) the fabrication of SiC-on-Insulator (SiCOI) stacks for light confinement; b) the development of device fabrication technology with SiCOI for integrated (quantum-) photonic circuits; c) Low loss and dispersion control as well as efficient coupling scheme for coupling light in and out of a chip by a dedicated (nano-)fabrication technology and material engineering.

Photonic integrated circuits (PICs) are widely used in optical communications and photonic computing. As the number of integrated components increases, the accumulation of fabrication-induced deviations degrades PIC performance, necessitating reliable post-fabrication trimming techniques. In this work, we introduce a non-invasive trimming method based on focused ion beam (FIB) deposition, enabling highly localized, room-temperature tuning of photonic components with minimal optical loss. We demonstrate its applicability to representative device structures and evaluate their optical response. This approach provides a practical and broadly compatible tool for enhancing the performance and scalability of next-generation PIC systems.

Atomic layer etching (ALE) is a process capable of etching surfaces with minimized damage, making it advantageous when used in conjunction with reactive ion etching (RIE) for integrated photonic applications. We have developed an ALE process for silicon carbide (SiC). Additionally, we will demonstrate the potential of ALE for surface smoothening and for reducing background radiation from disturbing defects.

Convolutional neural networks (CNNs) underpin many modern image and video processing systems. As these models grow in depth and complexity, they increasingly strain the capabilities of state-of-the-art digital hardware. Optical computing offers a promising alternative, thanks to its broad bandwidth, low latency, and the absence of capacitive charging limitations. In particular, time–wavelength interleaving provides an efficient way to map convolutional operations onto intertwined temporal and spectral domains, enabling high throughput signal processing. For scalable implementations, however, individual wavelength channels still need to be modulated by integrated de-multiplexing and wavelength-selective weighting elements. Herein, we present device architectures for de-multiplexing and weighting individual wavelength channels, integrated on a silicon-on-insulator platform using the imec iSiPP50G foundry process, thereby enabling compact and scalable optical neural-network computation.

In this work, we describe the design and modeling of integrated plasmonic chemical and biological sensors based on integrating optical waveguides and plasmonic nanostructures on silicon and silicon nitride platforms. Different architectures of the waveguides are investigated that allow maximum coupling of the guided modes in the waveguides to evanescently interact with the plasmonic nanostructures and excite localized surface plasmon resonances (LSPRs) in these nanostructures. The sensing regions in these sensor chips contain plasmonic structures and are integrated with the on-chip optical waveguides that carry the light to and from the sensing regions such that the transduction - in the light signal due to the change in refractive index of the surrounding medium due to a change in chemicals or due to the presence of the analyte molecules - can be detected.

We present an experimental evaluation of seven optical alignment algorithms tested on the Technoprobe Eclipse Dynamic probe card—a single-unit probe head that co-locates electrical probes and a piezoelectrically actuated fiber array unit, removing the need for external fiber positioners. Each algorithm was evaluated across eight distinct on-wafer die locations (spanning multiple reticle positions) directly on the hardware with the original actuator configuration (100 V/s slew rate, reset-to-zero hysteresis compensation). The measured trajectories were then used to simulate performance under three additional operating conditions: high-speed actuation (3250 V/s), direct-path routing without hysteresis resets, and the combination of both. Performance is compared using data- profile curves rather than averages alone, following established best practices for solver benchmarking. Among the candidates tested, Local Bayesian optimization and fixed gradient ascent both achieve 100% alignment success across all eight experimental scenarios. Under the original hardware configuration, Local Bayesian is the fastest among the 100%-success methods, converging in 100 a.u. per die. Simulations project that with high-speed actuation and direct-path routing, fixed gradient would achieve 4.6 a.u. per die while Local Bayesian would reach 17.2 a.u. The analysis reveals that eliminating hysteresis reset penalties contributes 2.2–5.6× speedup depending on algorithm, demonstrating that software-based path optimization can deliver substantial performance gains even without hardware upgrades. A phased development strategy is proposed to optimize throughput progressively through software and hardware improvements.

Soliton microcombs are established as reliable sources of low-noise, high-repetition-rate optical frequency combs, leveraging cascaded four-wave mixing in resonators with anomalous group-velocity dispersion (GVD). However, their intrinsic sech² spectral envelope limits their utility in applications like optical telecommunications, where a rectangular envelope with equal power per line is desired. Here, we introduce a novel method to control the spectral extent of microcombs using meta-dispersion in photonic crystal ring resonators. By patterning a complex corrugation along the resonator waveguide, we induce wavelength-dependent bidirectional coupling via Bragg reflection, hybridizing modes and precisely shifting resonance frequencies. This approach enables tailored control of the phase-matching condition, allowing us to shape the spectral envelope of the microcomb. We demonstrate this principle in both anomalous and normal GVD regimes: in the former, the soliton profile is strongly altered to enhance central lines; in the latter, we achieve comb generation in strongly normal dispersion waveguides, overcoming material dispersion by engineering near-zero meta-dispersion over a defined spectral range.

Nonlinear heterodyne interferometry is a sensitive, quantitative method for measuring the Kerr nonlinearity of integrated photonic waveguides. Using a frequency-shifted Mach–Zehnder interferometer to detect the amplitude and phase of femtosecond pulses enables the direct retrieval of the nonlinear phase shift within integrated waveguides. This method can accurately determine the nonlinear coefficient gamma over five orders of magnitude, ranging from silica fibres to chalcogenide glass and silicon waveguides. When combined with numerical modelling of the nonlinear Schrödinger equation, this approach can be extended to strong nonlinear regimes involving free carrier dynamics, where pulse reshaping, absorption, and carrier dispersion compete with the Kerr effect. This unified framework bridges nonlinear metrology and ultrafast dynamics, offering a direct alternative to Z-scan and four-wave-mixing techniques. It establishes nonlinear heterodyne interferometry as a robust diagnostic tool for next-generation photonic integrated circuits and emerging high-nonlinearity materials.

We present an experimentally-validated numerical model to evaluate the losses of rib and ridge-type straight waveguides that includes the contributions from all the waveguide surfaces and its use to derive the optimal geometry of lithium-niobate-on-insulator waveguides for low-loss propagation and for efficient three or four wave mixing nonlinear conversions. In each of these cases, the associated constraints and loss scaling laws allows the optimization to be reduced to a bi-dimensional parametric investigation using as parameters a morphology scanning factor and the in-plane-to-sidewall-roughness ratio. This way, the optimal waveguide geometry is shown to be the resulting trade-off between the surface roughness distribution, the modal effective areas and overlaps.

Four-wave mixing (FWM) offers promising applications in wavelength conversion, optical signal processing, and even quantum photonics. We report a study on the stimulated FWM in an integrated Q-InP channel waveguide based on a commercial foundry (SMART Photonics) at low power levels. Our results demonstrate that InP based channels exhibit high potential for nonlinear processes requiring lower input power levels, such as spontaneous four-wave mixing for single photon generation.

This paper will present an overview of the monolithic PIC technologies that are to be developed in the PIXEurope pilot line, which is one of the first five Chips JU pilot lines launched in Europe as part of the European Chips Act.. The five-year PIXEurope project started in June 2025 and a selection of the first results obtained since then will be reported. However, the main goal of the paper is to provide an introduction to all the different monolithic PIC platforms that are planned to be developed in PIXEurope and to explain their complementarity for different applications, wavelength ranges and end-user needs. In particular, the presentation will introduce PIC platforms based on indium phosphide, 220 nm and 3 µm thick silicon-on-insulator, silicon nitride, aluminum oxide, silicon carbide and germanium. Together these PIC platforms can fulfil the needs for both passive and active PIC components in the wavelength range from UV and visible all the way to mid-infrared. The development of design kits, hybrid integration, packaging and testing for the PICs in PIXEurope will also be briefly summarized.

The transfer of photonic technologies to commercial applications is now enabled by manufacturing initiatives. The shift also aligns with semiconductor industry standards, enabling better integration with existing manufacturing infrastructure. The design of a photonics pilot production facility requires a complex suite of technical, logistical and environmental challenges including precise control of particles, vibrations, electromagnetic interference, airborne chemical contamination, and temperature. Based on project case studies, including the design of an InP 6-inch pilot fabrication this presentation highlights solutions on how to balance the technical complexity with financial challenges and sustainability requirements. Lastly, a perspective will be presented how these experiences can drive us into integrated silicon photonics production facilities.

Integrated photonics is key to next-generation technologies, yet challenges remain in scalability, packaging, and testing. This talk reviews the state of the art in the main steps of next-generation PIC fabrication, like design, hybrid integration and packaging, and presents the novel technologies developed within PIXEurope to accelerate industrial adoption, reduce costs, and enable high-performance photonic systems.

Advanced integrated photonics components deliver and promises unprecedented functions with very compact format, mass manufacturability and lower power consumption than legacy systems. The components being developed for photon generation, manipulation, emission, reception and detection have complex geometries and very small dimensions, making their optical interfacing and overall assembly and packaging very demanding. Micro-optics improves dramatically these optical interfaces by improving the photon emission efficiency, detection efficiency and coupling efficiencies between integrated photonic devices as will be discussed in various cases. Stand-alone micro-optics components allowed dramatic cost reduction in various industries such as for light to fiber coupling, consumer electronics devices or automotive. A few examples of such stand alone micro-optics are presented, such as to miniaturize compact optical atomic clocks. However, integrating micro-optics together with integrated photonic devices offers further miniaturization, ease of assembly and unmatched performance and allow to address emerging needs in a variety of cases. Single‑photon detectors and imagers such as single‑photon avalanche diode (SPAD) arrays, silicon photomultipliers (SiPMs), and advanced CMOS image sensors are intrinsically limited by pixel fill factor, dead areas, and optical losses at the detector surface. However, they allow unmatched low light detection sensitivity, up to single photon detection capability, at room temperature. These limitations are particularly critical under photon‑starved conditions relevant to scientific instrumentation, quantum sensing, time‑resolved imaging, and super-resolution microscopy. Monolithically integrated microlens arrays provide an effective means to increase the effective photon collection area by concentrating incident light onto the active regions of the detector, boosting the quantum efficiency of these photon detectors. CSEM has developed a UV‑replication‑based microlens technology enabling the fabrication of a wide variety of microlens arrays with diameters ranging from a few micrometers to the millimeter scale. Microlenses can be fabricated from a variety of materials, including inorganic sol‑gels and organic polymers such as PMMA and polyurethane, allowing optimization with respect to optical transmission, mechanical stability, environmental robustness, and application‑specific constraints. The technology is compatible with wafers up to 8″ but as well down to individual chips down to 2 × 2 mm². The technology is compatible with aggressive environment such as space and cryostats. The impact of UV‑replicated microlenses has been evaluated on several classes of quantum photonic devices. For front‑illuminated SPAD imagers, cylindrical and square microlenses significantly increase the photon concentration factor, with measured values of approximately 2 to 9 in agreement with optical simulations. In low‑photon‑flux regimes, these microlenses enhance signal‑to‑noise ratio by increasing the number of detected photons without introducing additional electronic noise. Various optimization techniques are presented to further improve the imagers and detectors. In the context of high‑energy physics, round microlenses integrated on silicon photomultipliers developed for the upgrade of the Large Hadron Collider b detector at CERN achieve pixel fill factors exceeding 80% and enable approximately 15% more detected photons at room temperature as well as in cryostats. In a different direction, the rapid growth of data communications, cloud computing, and AI infrastructure is driving an increasing demand for high‑density optical interconnects capable of supporting large fiber counts while maintaining reliability in demanding environments. Conventional physical‑contact fiber connectors face significant challenges in such applications, including stringent sub‑micron alignment tolerances, high sensitivity to contamination, and reduced mechanical robustness as the number of fibers per connector increases. These limitations become particularly critical in telecom, datacom, defense, and industrial networks, where connectors must operate reliably over wide temperature ranges and under harsh environmental conditions. Expanded beam (EB) fiber connector technology offers an attractive alternative by eliminating direct fiber‑to‑fiber contact. By expanding, collimating, and refocusing the optical beam between mating fibers, EB connectors significantly relax alignment and cleanliness requirements. However, traditional EB implementations often rely on glass or polymer lenses that suffer from either high cost or strong thermal and environmental sensitivity, limiting scalability and stability. We have been developing a next‑generation multi‑fiber optical connector based on expanded beam technology using thermally compensated polymer microlens arrays fabricated and assembled at wafer level. The connector is developed by Zoharay in collaboration with CSEM, VTT, and TH‑Wildau, combining optical system design, advanced micro‑optical fabrication, material characterization, and precision bonding technologies. The core innovation lies in the use of polymer microlens doublets with matched thermo‑optic and thermo‑mechanical properties, enabling stable optical performance across a wide temperature range while retaining the cost and scalability advantages of polymer optics. The connector architecture consists of three main elements: a commercially available MT/MPO multi‑fiber ferrule, an optical insert incorporating the microlens arrays, and a mating interface ensuring repeatable alignment. The ferrule provides accurate fiber positioning through standard guiding holes and alignment pins, enabling compatibility with existing datacom ecosystems. Within the optical insert, paired polymer microlenses expand and collimate the beam, significantly reducing sensitivity to dust particles and lateral misalignment. Optical simulations and ray‑tracing optimization demonstrate a numerical aperture of approximately 0.22 and a coupling loss sensitivity below 0.3 dB for lateral misalignments of ±5 µm, while showing strongly reduced temperature dependence compared to conventional single‑lens EB designs. The resulting connector system targets multimode fiber arrays operating at 850 nm and supports high fiber densities while maintaining low insertion loss, high return loss, and robust environmental performance. Its compatibility with existing MPO‑based infrastructure makes it particularly attractive for large‑scale deployment in data centers, telecom networks, and harsh‑environment applications where conventional physical‑contact connectors reach their limits. In a third direction, micro-optics assembly on photonic integrated circuits (PIC) for waveguide array to fiber array unit (FAU) coupling is today a key enabler for advanced electronic and photonic packages, so called co-package optics. Co-package optics is widely evaluated as being key to reduce the energy consumption of datacenters while providing higher bandwidth inside each rack unit. Examples of implementation in the industry of micro.optics for PIC to FAU coupling are presented to review the current state of the art. Current limitations and expected future development in this strategic field are presented as well as the challenges to enable mass manufacturing of this micro-optics-enabled co-package optics systems.

Broadband and efficient vertical coupling remains a major challenge in silicon photonics. Conventional grating couplers enable efficient fiber-to-chip coupling but offer a limited bandwidth of around 30 nm, which restricts their use in applications such as wavelength-division multiplexing. In this work, we propose a new fiber-to-chip coupling architecture based on a standard silicon-on-insulator (SOI) platform, composed of a 45° planar reflector and a metalens. We optimized the coupler to operate around 1550 nm. Finite-difference time-domain (FDTD) simulations demonstrate a maximum coupling efficiency of -0.73 dB and a 1 dB bandwidth of 300 nm. An alternative optimization strategy increases the bandwidth to 430 nm, at the expense of a slightly lower maximum coupling efficiency of –0.88 dB.

Efficient coupling between photonic integrated circuits (PICs) and optical fibers is one of major challenges in single-mode co-packaged optics (CPO) due to stringent alignment tolerance requirements. We present a detachable, free-space, expanded beam optical coupling between a fiber array (FA) and a photonic integrated circuit (PIC) using single-mode micro lens arrays (MLAs) molded from a novel solder-reflow resistant thermoplastic (EXTEM™ RH1017UCL) resin. Such an MLA could offer a cost-effective solution for mass production of optical interconnects. The MLAs, which consisted of eight lenses with a 250 micron pitch, facilitate either edge- or surface-coupling with high reproducibility across detachable operations due to significant relaxation of alignment tolerances between FA and PIC. Design concepts uncovered by simulation to mitigate effects of CTE difference between a thermoplastic MLA and the PIC is also discussed, for example when exposed to a high power external laser source (ELS).

We present a novel photonic architecture that leverages broadband chaotic-light as an entropy source together with an incoherent photonic crossbar array to enable high-speed probabilistic computation. By encoding input means and variances in the optical domain and performing parallel wavelength-division-multiplexed sampling, we execute probabilistic convolutions and embed a Bayesian neural network capable of both classification and uncertainty estimation. Our prototype processes at an effective sampling rate of tens of gigasamples per second and demonstrates high accuracy on the MNIST task while reliably detecting out-of-distribution inputs. This work paves the way for ultrafast hardware-native probabilistic inferencing.

We present a photon statistics transducer — a high-extinction, broadband electro-optic device that enables real-time, voltage-programmable control of photon-number distributions. Using a cascaded thin-film lithium niobate (TFLN) Mach–Zehnder amplitude modulator with >50 dB extinction, we deterministically switch light between Poissonian and super-Poissonian regimes on nanosecond timescales. By combining coherent seeding with erbium-amplifier dynamics, the device tunes the second-order coherence from 𝑔(2)(0)=1.0 to 1.7 and allows photon-flux control down to sub-photon levels, verified with superconducting nanowire detectors. This establishes statistical modulation as a new functional primitive for integrated photonics, enabling entropy-aware signal processing, secure communication, and hybrid quantum-classical systems.

Current trends in quantum communication search for efficient platforms that could leverage a low power con- sumption and good scalability. Relevant to this, integrated photonics poses advantages against free space optics. Several materials have been studied, looking for a reduction in power consumption, losses from several sources, and high-speed modulation. This work explores the application of thin-film lithium niobate (TFLN) as a novel platform for photonic integrated circuits (PIC)-based optical intersatellite telecommunications. This material is suited for this application due to its outstanding bandwidth and low power draw for electro-optic modulation. We characterize different loss sources in passive elements and test active elements using both electro-optic and thermo-optic interactions for high-speed modulation and fine bias tuning, respectively. An architecture for IQ modulation is tested and compared with its free-space optics counterpart, showing the viability of integrated photonics for communication applications.

Integrated photonic platforms provide a powerful route toward scalable and stable quantum light sources. In this presentation, we explore how quantum correlations can be generated, distributed, and characterized in the frequency domain using integrated photonic frequency combs. Relying on Kerr nonlinear microresonators operated below and above threshold, we demonstrate the generation of discrete entangled photon pairs as well as bright multipartite quantum states involving many spectral modes. We show how frequency multiplexing enables both multi-user quantum communication and enhanced data rates, while remaining fully compatible with integrated photonic circuits. Beyond bipartite entanglement, we report direct signatures of genuine multipartite quantum correlations in bright frequency combs. These results highlight integrated photonics as a versatile and scalable platform for multimode quantum technologies in communication, sensing, and metrology.

Free-space optical systems are strongly affected by atmospheric turbulence, which distorts the optical wavefront and degrades signal integrity. This work demonstrates a chaos-based free-space optical link at 1.55 µm that remains robust under turbulence through the use of a programmable optical processor (POP) acting as a multi-aperture self-configuring receiver. The turbulent channel is emulated in the laboratory using a spatial light modulator (SLM) implementing random phase screens based on the Modified von Kármán spectrum. Implemented on a silicon photonic platform, the POP adaptively reconfigures itself via a control algorithm that maximizes optical power, compensating for phase distortions in real time. By restoring the chaotic waveform dynamics lost under turbulence, the POP showcases the potential of adaptive photonic receivers to enhance the resilience, stability, and reliability of future free-space optical systems.

Born’s rule links the quantum wavefunction to measurable probabilities, yet its derivation from more fundamental principles remains unresolved. A key implication, which is that interference occurs only between pairs of paths, can be tested using multi-path interferometers that search for higher-order interference via the Sorkin Test. We implement a three-path interferometer on a photonic chip, providing stability and compactness suitable for extreme environments, including space. The device, based on femtosecond laser-written waveguides with thermal phase shifters, is characterized in the laboratory and calibrated for temperature effects. A twin chip with an integrated MoSe₂ photon source is deployed on a 3U CubeSat to evaluate its functionality for a space-based Sorkin Test.

We demonstrate an optical true-time-delay (OTTD)–based RF beamforming system using a 5-bit, 4-channel OTTD chip fabricated on VTT’s low-loss 3-µm SOI platform. Operating in the C-band, the device offers 32 delay states (0–100 ps), enabling full 2π phase control at 10 GHz. The platform’s ~0.1 dB/cm loss supports long delay lines. At the same time, OTTD-based beamforming provides advantages in power efficiency, bandwidth, footprint, cost, and EMI immunity, positioning it as a promising technology for future 6G systems.

Volumetric printing by reverse tomography—commonly referred to as tomographic volumetric additive manufacturing (TVAM), or simply VAM—is a layerless 3D printing approach that creates solid objects by projecting sequences of light patterns into a rotating photosensitive resin. The cumulative energy deposition leads to localized photopolymerization, enabling the fabrication of complex 3D structures within seconds. Since its first demonstration in 2019, TVAM has rapidly gained attention and has been extended to a wide range of materials, including polymers, hydrogels, ceramics, metals, and glass. Despite these advances, several fundamental challenges remain: expanding the achievable build volume, improving resolution toward that of two-photon polymerization, and extending the method to non-transparent or composite resins. Beyond these technical hurdles, TVAM also opens unique opportunities not accessible to traditional additive manufacturing techniques—for example, the ability to fabricate directly around existing structures. This talk will review the progress of the field, highlight key developments, and explore emerging strategies to address current limitations while pointing toward new application domains.

Hollow core fibres (HCFs) guide light through a gas-filled core rather than solid glass and offer unique optical properties and transformative potential. Recent breakthroughs have reduced losses to levels below those of conventional silica fibres across a broad spectrum—from the ultraviolet to the mid-infrared. While these advances were primarily driven by applications in high-capacity data transmission, the capabilities of HCFs extend far beyond communications. They enable enhanced light–matter interactions, exceptional radiation hardness and low non-linearity for sensing applications such as gas detection and precision gyroscopes. There is even the prospect of light transmission in vacuum, pushing towards ultimate waveguide performance. As fibre designs improve, controlling the internal gas composition and pressure becomes critical, driving progress in gas dynamics modelling, advanced characterisation, and post-processing techniques. This talk will explore recent progress in HCF technology, the pivotal role of gas in transmission, and the opportunities and challenges of guiding light through a hollow core.

Photonic integrated circuits (PICs) in datacom/computing and select applications are now essential components; but post-Moore’s Law performance scaling leads to underdetermined electronic-photonic device innovation and materials integration. This requires a continuous workforce training curriculum and methodology, to periodically upskill in iterating High Volume Manufacturing standards for PICs and Co-Packaged Optics (CPO). Findings from the Integrated Photonic Systems Roadmap-International have informed a dual (i) synchronous and (ii) asynchronous curricula and design-based methodology: (i) a graduate-to-industry program with project-based learning, and test/packaging bootcamp; (ii) online MOOCs reinforced with VR or digital twin/game simulators. This approach emphasizes application-specific training, using project-based and gamified learning. Previous accomplishments in design-based training will be reviewed as prelude to AI computing, whose energy demands compel a need for joint training in CPO and Life Cycle Assessment curricula; online and gamified content will be presented. Finally, hybrid learning will be discussed, with prospects to autonomously deploy within industry.

Photonic integrated circuits (PIC) have become the backbone of modern telecom infrastructure, and are a key driving force for future sensing, communication, display, and computing systems. The rapid growth of this technology is creating demand for a rapidly expanding and correspondingly skilled workforce. Conventional education programs offered by universities cover foundational, systematic understanding for device physics and circuit implementations, but often provides limited hands-on experience. In contrast, many practical skills including circuit design, foundry processes, testing, packaging, remain less accessible and less structured. This creates a growing skill gap. Addressing the gap requires targeted training programs for the PIC value chain. This presentation introduces training development efforts at TU Eindhoven, covering key existing activities in the JePPIX ecosystem. New projects including Phortify and DECIDE are then highlighted in the context of how they support the PIC value chain and contribute to focus areas like manufacturing and testing. In addition, executive-level business trainings aim to stimulate entrepreneurship, investment, and informed policymaking. Together, these programs form a coordinated training landscape that strengthens the talent pipeline supporting the growth of the Dutch and European PIC industry.

This talk introduces the training opportunities offered through the PIC Bootcamp program. PIC Bootcamp brings together academic and industrial partners to provide accessible, hands-on training for participants at all levels of expertise. The modular structure of the training sessions covers the Photonic Integrated Circuit (PIC) ecosystem, including design, fabrication, and packaging. By combining academic knowledge with industry-relevant practices, PIC Bootcamp aims to equip participants with the practical skills needed in the rapidly growing PIC sector.

Plasmonic nanostructures enable strong electromagnetic field enhancement and subwavelength light confinement, making them highly attractive for optical biosensing. However, conventional surface plasmon resonance sensors rely on external light sources and bulky optical components, limiting their portability and on-chip integration. Here, we present a self-illuminating plasmonic biosensor that operates without any external optical excitation. The device integrates a metal–insulator–metal tunnel junction with a plasmonic metasurface, enabling intrinsic light generation via inelastic electron tunneling. The generated photons couple efficiently to plasmonic lattice modes, providing high sensitivity to refractive index changes at the sensor surface. The gold metasurface simultaneously serves as an electrical contact and a plasmonic resonator, allowing direct electrical-to-optical transduction. The device exhibits uniform emission over a large area under low bias and supports well-defined plasmonic modes that govern the emission spectrum. Biosensing performance is demonstrated using polymer films and biofilms, achieving detection sensitivity comparable to state-of-the-art passive plasmonic sensors. This compact, label-free platform offers strong potential for integration into next-generation biosensing and diagnostic systems.

Monitoring the frequency detuning between a laser and an optical microring resonator (MRR) is critical for the stable operation of many cavity-enhanced photonic systems. We propose a simple method for detuning monitoring based on frequency-swept phase modulation. A swept electrical signal drives an electro-optic phase modulator (EOM) to generate optical sidebands around the pump laser. When the modulation frequency is scanned, the output of the photodector (PD) exhibits a dip as soon as one of the sidebands overlaps with the cavity resonance. The modulation frequency corresponding to the dip therefore directly indicates the laser–cavity detuning. A theoretical model of the detected signal is derived and verified through numerical simulations. The results reveal a clear mapping between modulation frequency and detuning, and demonstrate that the readout remains robust over a wide range of modulation depths and coupling conditions. The proposed approach provides a simple and practical solution for detuning monitoring in integrated photonic resonator systems.

We present a fully integrated, phase-stable interferometric excitation scheme for photonic resonators on a silicon-on-insulator platform. Using thermal tuning, the device enables coherent excitation from two input ports, allowing estimation of the complex eigenvalues of any non-Hermitian microresonator. This system is demonstrated on an Infinity-Loop Microresonator–a non-Hermitian infinity-shaped microresonator with both lobes coupled to a bus waveguide. We described its optical behavior by means of an extended Temporal Coupled Mode Theory, capturing phase-controlled interference between the excitation fields. This approach allows precise manipulation of the resonator’s spectral response. Our platform not only provides a tool for characterizing non-Hermitian photonic systems but also opens new opportunities for exploring complex topological and programmable photonic devices.

Dynamic switching of the light propagation is a key enabler for integrated nanophotonic circuits. Optical gratings are a widely used, versatile component for coupling light into and out of waveguides. However, their diffraction efficiency is generally set and limited well below unity by static design and process parameters such as etch depths or geometric profile quality. We experimentally demonstrate the use of a dielectric-mirror cavity for enhancing the diffraction efficiency of grating couplers beyond these intrinsic limits. Using a second counterpropagating input beam achieves near-perfect dynamic control of the coupling amplitude. The experiments are backed by analytical and numerical modeling of the cavity-enhanced diffraction efficiency and the interaction of light waves in optical-gratings multiport devices. These findings extend the concept of coherent perfect absorption (CPA) from thin absorbing layers to diffractive structures, providing an all-optical propagation switching mechanism for efficient signal input and control in compact photonic circuits and nano-optic systems.

Scalable test, assembly, and packaging processes are being developed to support dense electronic-photonic integration in high-volume production flows. Electronic, photonic, and micro-optic components have to be combined in a small form factor on a common substrate, fulfill demanding performance and cost expectations from the application perspective, while supporting efficient scaling for volume production environments. Test flows, processes, and tools for validation of parts, subsequent assembly steps, and functional verification of the final packages are being established. Convergence with existing semiconductor standards and the enablement of efficient design are essential for a wide adoption of such heterogeneous technologies. A design flow featuring a heterogeneous process design kit has been created for the JEDEC-compliant, glass-based electronic-photonic packaging technology developed in the PhotonicLEAP project, and will be demonstrated. The PhotonicLEAP process design kit enables a seamless design process while capturing front-end process from multiple sources, along with back-end (assembly and packaging) and test.

Phase-change materials (PCMs) offer broadband, non-volatile, and reversible control of optical properties, making them promising candidates for reconfigurable integrated photonics. In this work, we experimentally demonstrate the electrical programming of multilevel optical reflectivity in a SiO2/GST/SiO2 thin-film stack operating in the near-infrared range. Platinum micro-heaters integrated into the structure are engineered to operate near the critical-coupling condition, enhancing reflectivity contrast during progressive crystallization of Ge2Sb2Te5 (GST). By applying voltage pulses of fixed amplitude with increasing duration and repetition, we achieve precise and gradual modulation of optical reflectivity, yielding more than 50 stable intermediate states between the amorphous and crystalline phases. These results demonstrate fine electrical control of optical properties in GST-based devices, paving the way toward scalable electro-photonic platforms for programmable metasurfaces, spatial light modulators, and neuromorphic photonics.

Monolithic integration of polarization splitters is crucial for effective polarization management in photonic integrated circuits (PICs). This work presents a broadband polarization splitting technique using adiabatic couplers and compact total internal reflection mirrors on a thick silicon-on-insulator platform. The approach provides wavelength-independent and polarization-dependent phase shifts. Recent demonstrations achieved over 15 dB polarization extinction ratio across a 450 nm wavelength range, supporting applications in optical communication, healthcare, and quantum optics.

We demonstrate a narrow bandwidth, thermally tunable optical filter based on higher-order coupled resonator optical waveguides (CROWs) in post-CMOS compatible low-temperature plasma-enhanced chemical vapor deposition (PECVD) silicon nitride waveguide. The device shows high out-of-band extinction ratio, a box-like spectral response with steep roll-off, and a few-GHz 3 dB bandwidth suitable for resolving closely spaced lines such as in optical frequency combs. We use Ti/TiN heaters to achieve optical tunability of the filter for selecting different wavelength inputs and to mitigate variations in spectral responses induced by fabrication imperfections. The post-CMOS compatible SiN platform paves the way for co-integration of photonics and driving electronics on a single chip in the future.