CMC Electronics, Inc.

The Short-Wave InfraRed (SWIR) spectral region is emerging as a promising operating band for next-generation active sensing, laser range finding, and countermeasure receivers, offering lower scattering losses, enhanced eye safety, and improved atmospheric transmission. However, the performance of detectors operating in this transitional region between extended-InGaAs and InGaAsSb remains limited by increased dark current, junction capacitance, and lack of high-efficiency avalanche gain. This paper highlights the limitations of available detectors operating in this wavelength range and the performance that can still be achieved when assembled in CMC Electronics’ products. Hybrid integration with ultra-low noise transimpedance amplifier (TIA) achieves noise-equivalent power (NEP) values as low as 0.8 pW/√Hz at 10 MHz for small-area detectors, and below 6 pW/√Hz for 270 pF devices at 10 MHz, at room temperature. Simulations show a 3–4× NEP advantage of the CMC hybrid over conventional PCB-mounted COTS TIA designs, translating directly into a corresponding 3.75× reduction in the required transmitter peak power for equal detection range.

This paper presents the development of a COTS 1-mm InGaAs PIN quadrant photodetector for high precision beam tracking in Laser Spot Trackers (LSTs), Precision-Guided Munitions (PGMs), Laser Warning Systems (LWS), and Free Space Optical (FSO) terminal alignment. Targeting defense and aerospace platforms where Size, Weight, Power, and Cost (SWaP-C) are tightly constrained, the module integrates a 1-mm active-area InGaAs PIN photodiode segmented into four quadrants with four application-specific GaAs FET transimpedance amplifiers (TIAs) in a single hermetic TO-can package, delivering a compact solution optimized for high-sensitivity detection for use in mobile or ruggedized defense platforms.

Optimizing the architecture of a NIR optical receiver can significantly enhance detection performance. Achieving this improvement requires a detailed understanding of the photodetector’s intrinsic characteristics—such as gain, excess noise, capacitance - as well as the constraints imposed by the chosen assembly technology, whether implemented with discrete PCB components or through hybrid integration. These factors ultimately define the fundamental noise bandwidth compromise that governs overall receiver sensitivity. This paper examines the impact of key design parameters on InGaAs avalanche photodiode based receivers, outlining how topology, biasing, and front end electronics influence system level performance. Three receiver families are presented, each optimized for specific mission profiles: defend, detect, and communicate. Potential customization paths for enhanced sensitivity, extended bandwidth, or improved environmental robustness are also discussed to guide future development.