Li Baoshuai, Wang Weiqiang, Yang Honglei, Liu Hao, Chu Sai T, Little Brent, Song Yuxia, Guan Boren, Zhang Wenfu, Li Mingyu
Appl Opt. 2023 May 10;62(14):3772-3777. doi: 10.1364/AO.486492.
Integrated narrow-linewidth lasers are the key devices in compact coherent optical systems of metrology, sensing, and optical microwave generation. Here, we demonstrate a hybrid integrated laser based on an optical negative feedback scheme. The laser is composed of a commercial distributed feedback (DFB) laser diode and an on-chip micro-resonator with a Q-factor of 0.815 million. The feedback optical field is coupled back to the laser cavity through the back facet. Therefore, the laser can maintain the lasing efficiency of the DFB laser diode. The linewidth of the DFB laser diode is compressed from 2 MHz to 6 kHz, corresponding to the linewidth reduction factor of 25.2 dB. The theoretical result shows that the laser performance still has a huge improvement margin through precise control of the detuning between laser frequency and the micro-resonator, as well as the phase delay of the feedback optical field. The hybrid narrow-linewidth laser diode has wide application prospects in coherent optical systems benefitting from the low cost and volume productivity.
集成窄线宽激光器是计量、传感和光学微波产生等紧凑型相干光学系统中的关键器件。在此，我们展示了一种基于光学负反馈方案的混合集成激光器。该激光器由一个商用分布反馈（DFB）激光二极管和一个品质因数为81.5万的片上微谐振器组成。反馈光场通过后端面耦合回激光腔。因此，该激光器能够保持DFB激光二极管的激射效率。DFB激光二极管的线宽从2 MHz压缩至6 kHz，对应线宽压缩因子为25.2 dB。理论结果表明，通过精确控制激光频率与微谐振器之间的失谐以及反馈光场的相位延迟，激光器性能仍有巨大的提升空间。这种混合窄线宽激光二极管因其低成本和批量生产能力，在相干光学系统中具有广阔的应用前景。
