Wunderer, ThomasSiddharth, AnatJohnson, Noble M.Chua, Christopher L.Teepe, MarkYang, ZhihongBatres, MaxMaeda, PatrickLihachev, GrigoryKippenberg, Tobias J.2023-08-142023-08-142023-08-142023-06-0110.1364/OL.486758https://infoscience.epfl.ch/handle/20.500.14299/199740WOS:001016510600003Chip-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 GroupOpticsultravioletplatformnoisetext::journal::journal article::research article