Single-frequency violet and blue laser emission from AlGaInN photonic integrated circuit chips

Chip-based, single-frequency and low phase-noise integrated photonic laser diodes emitting in the violet (412 nm) and blue (461 nm) regime are demonstrated. The GaN-based edge-emitting laser diodes were coupled to high-quality on-chip micro-resonators for optical feedback and mode selection resulting in laser self-injection locking with narrow emission linewidth. Multiple group III-nitride (III-N) based photonic integrated circuit chips with different waveguide designs including single-crystalline AlN, AlGaN, and GaN were developed and characterized. Single-frequency laser operation was demonstrated for all studied waveguide core materials. The best side-mode suppression ratio was deter-mined to be similar to 36 dB at 412 nm with a single-frequency laser emission linewidth of only 3.8 MHz at 461 nm. The perfor-mance metrics of this novel, to the best of our knowledge, type of laser suggest potential implementation in next-generation, portable quantum systems. (c) 2023 Optica Publishing Group