Recent advancements in ultra-low-loss silicon nitride (Si3N4)-based photonic integrated circuits have surpassed fiber lasers in coherence and frequency agility. However, high manufacturing costs of DFB and precise control requirements, as required for self-injection locking, hinder widespread adoption. Reflective semiconductor optical amplifiers (RSOAs) provide a cost-effective alternative solution but have not yet achieved similar performance in coherence or frequency agility, as required for frequency modulated continuous wave (FMCW) LiDAR, laser locking in frequency metrology, or wavelength modulation spectroscopy for gas sensing. Here, we overcome this challenge and demonstrate an RSOA-based and frequency-agile fully hybrid integrated extended distributed Bragg reflector (E-DBR) laser with high-speed tuning, good linearity, high optical output power, and turn-key operability. It outperforms Vernier and self-injection locked lasers, which require up to five precise operating parameters and have limitations in continuous tuning and actuation bandwidth. We maintain a small footprint by utilizing an ultra-low-loss 200 nm thin Si3N4 platform with monolithically integrated piezoelectric actuators. We co-integrate the DBR with a compact ultra-low-loss spiral resonator to further reduce the intrinsic optical linewidth of the laser to the Hertz-level—on par with the noise of a fiber laser—via self-injection locking. The photonic integrated E-DBR lasers operate at 1550 nm and feature up to 25 mW fiber-coupled output power in the free-running and up to 10.5 mW output power in the self-injection locked state. The intrinsic linewidth is 2.5 kHz in the free-running state and as low as 3.8 Hz in the self-injection locked state. In addition, we demonstrate the suitability for FMCW LiDAR by showing laser frequency tuning over 1.0 GHz at up to 100 kHz triangular chirp rate with a nonlinearity of less than 0.6% without linearization by modulating a Bragg grating using monolithically integrated aluminum nitride (AlN) piezoactuators.

中文翻译：

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压电可调谐窄线宽光子集成扩展 DBR 激光器


超低损耗氮化硅（Si 3氮4基于光子集成电路的相干性和频率捷变性已经超越了光纤激光器。然而，DFB 的高制造成本和自注入锁定所需的精确控制要求阻碍了广泛采用。反射式半导体光放大器 (RSOA) 提供了一种经济高效的替代解决方案，但尚未达到调频连续波 (FMCW) LiDAR、频率计量中的激光锁定或波长调制光谱所需的相干性或频率捷变性方面的类似性能。气体传感。在这里，我们克服了这一挑战，并展示了一种基于 RSOA 的频率捷变全混合集成扩展分布式布拉格反射器 (E-DBR) 激光器，具有高速调谐、良好的线性度、高光输出功率和交钥匙可操作性。它的性能优于游标激光器和自注入锁定激光器，后者需要多达五个精确的操作参数，并且在连续调谐和驱动带宽方面存在限制。我们利用超低损耗 200 nm 薄硅来保持较小的占地面积3氮4具有单片集成压电执行器的平台。我们将 DBR 与紧凑型超低损耗螺旋谐振器共同集成，通过自注入锁定进一步将激光器的固有光学线宽降低至赫兹级，与光纤激光器的噪声相当。光子集成 E-DBR 激光器的工作波长为 1550 nm，在自由运行时具有高达 25 mW 的光纤耦合输出功率，在自注入锁定状态下具有高达 10.5 mW 的输出功率。自由运行状态下的固有线宽为 2.5 kHz，低至 3。自注入锁定状态下为 8 Hz。此外，我们还通过使用单片集成氮化铝 (AlN) 压电执行器调制布拉格光栅，以高达 100 kHz 三角啁啾速率在 1.0 GHz 上调谐激光频率，非线性度小于 0.6%，无需线性化，从而证明了 FMCW LiDAR 的适用性。