Widely tunable 2 µm hybrid laser using GaSb semiconductor optical amplifiers and a Si₃N₄ photonics integrated...

Tunable lasers emitting in the 2-3 µm wavelength range that are compatible with photonic integration platforms are of great interest for sensing applications. To this end, combining GaSb-based semiconductor gain chips with Si₃N₄ photonic integrated circuits offers an attractive platform. Herein, we utilize the low-loss features of Si₃N₄ waveguides and demonstrate a hybrid laser comprising a GaSb gain chip with an integrated tunable Si₃N₄ Vernier mirror. At room temperature, the laser exhibited a maximum output power of 15 mW and a tuning range of ∼90 nm (1937-2026 nm). The low-loss performance of several fundamental Si₃N₄ building blocks for photonic integrated circuits is also validated. More specifically, the single-mode waveguide exhibits a transmission loss as low as 0.15 dB/cm, the 90° bend has 0.008 dB loss, and the 50/50 Y-branch has an insertion loss of 0.075 dB.