Widely Tunable (2.47–2.64 µm) Hybrid Laser Based on GaSb/GaInAsSb Quantum‐Wells and a Low‐Loss Si₃N₄ Photonic Integrated Circuit

Abstract

Abstract Photonic integrated circuits fabricated using a Si 3 N 4 waveguide platform exhibit low losses in a wide wavelength region extending from visible to beyond 2 µm. This feature is exploited to demonstrate a high‐performance integrated laser exhibiting broad wavelength tuneability near a 2.6 µm wavelength region. The laser is based on a Si 3 N 4 photonic integrated circuit incorporating a tunable reflector and a AlGaInAsSb/GaSb quantum‐well gain element. A tuning range of 170 nm (2474–2644 nm) and single‐mode CW operation with a maximum power of 6.4 mW at room temperature are demonstrated. The performance is enabled by exploitation of several essential building blocks realized in Si 3 N 4 , namely low‐loss Y‐branches, inverse tapers, and a double‐ring resonator with a free spectral range of ≈160 nm. Moreover, the limits of wavelength coverage are explored using Si 3 N 4 waveguides and show that the platform supports low propagation loss up to 3.5 µm. Finally, the possibility to achieve improved mode matching between Si 3 N 4 and GaSb waveguides is analyzed, further enabling enhancing the performance of such a hybrid laser platform and supporting wavelength extension beyond a 3 µm range.