Femtosecond laser processing of an integrated fiber Fabry-Perot cavity device in glass

High-finesse optical microcavities are at the core of a wide range of scientific advances and technical applications from quantum technologies to optical sensors. Among them, fiber Fabry-Perot cavities (FFPCs) are of particular interest because of their unique properties. However, integrating FFPCs into photonic devices remains an experimental challenge prone to errors. To tackle this limitation, we combined FFPCs with femtosecond laser manufacturing to assemble an all-glass FFPC integrated on a microstructured glass substrate with a reduced footprint (25x25 mm). Cavity finesse reached prior to fine tuning exceeded 60 000. Post-assembly fine tuning is performed only once. Our manufacturing approach paves the way for miniaturized ‘all-glass’ FFPC chips with extreme sensitivities that can be deployed outside the labs finding applications in gas sensing applications and quantum technologies.