Widely Tunable GaSb/Si3N4 Vernier Hybrid Laser Emitting Around 2.55 µm

The development and characterization of a GaSb/Si3N4 tunable Vernier hybrid laser is presented. We combined a GaSb-based reflective semiconductor amplifier to provide feedback and gain, with a reflective Si3N4 circuit to provide wavelength tuning and filtering. The Si3N4 circuit comprises two thermally tunable ring resonators within a loop mirror configuration towards Vernier type operation. Operating at an emission wavelength of 2.55 µm, this laser exhibits a low threshold current of 190 mA and achieves a continuous-wave output power of 6.4 mW at 325 mA. Notably, it demonstrates a wide tuning range of 170 nm (2474–2644 nm) at 325 mA injection current, delivering a consistent output power of 5 mW within the central band (2520–2620 nm) and maintaining >1 mW even at the band edges. These characteristics provide unique advantages for possible use in a wide range of sensing applications, from spectroscopic sensing of gases to detection of biomarkers.