In this Phase 2 SBIR Trex and Columbia propose to fabricate the SWIR optical comb concept that was developed in Phase 1 that is centered at 1550nm and has > 100 lines with 100 GHz FSR, 200+ uW/line, >45 dB side-mode suppression, and all lines are phased together. This is a hybrid device consisting of a reflective semiconductor optical amplifier (RSOA) that is coupled to a dual-ring Si3N4 (SiN) microresonator. The microresonator serves as both the optical comb generator, and the output mirror for the (RSOA). The goal of this Phase 2 SBIR is to prove that this device can be fabricated at a silicon foundry for low-cost manufacturability. To enable this we propose to etch the ring-resonator waveguides into the silicon, and then bond a thin layer of SiN over the top. Simulations show that with the SiN in close proximity to the silicon waveguide that most of the mode energy is concentrated in the SiN layer and sees its dispersion. The hybrid device has a smaller footprint and more compact package than separate source and resonator solutions. The dual rings give the microresonator flexibility in compensating for manufacturing errors in the waveguide fabrication, thus improving device yield.
