Heterogeneously‐integrated lasers on thin film lithium niobate

Abstract We demonstrate a versatile heterogeneous integration platform unifying III–V gain with thin‐film lithium niobate (TFLN) photonic circuits to create high‐performance lasers with integrated functionality. This breakthrough overcomes the critical barrier to fully integrated photonic systems by combining optical gain, low‐loss cavities, and phase control on a single chip. We present two distinct laser architectures: a distributed feedback laser achieving 11.0 kHz intrinsic linewidth and 4.0 mW in‐fiber power through self‐injection locking to a high‐ Q TFLN resonator, and a Vernier ring laser exhibiting 44 nm continuous tuning range with 40 dB side‐mode suppression ratio. Crucially, the heterogeneous integration of the gain section with TFLN’s components provides a promising path to implementing direct intracavity modulation, which is a functionality that typically requires discrete components. This inherent capability makes our platform a foundational advancement for future compact, robust systems in coherent communications, ultrafast optical metrology, quantum photonic processors, and microwave photonic systems operating at GHz bandwidths, marking a significant advancement toward complete photonic system integration.