DFB半导体激光器自注入锁定失稳因素分析

分布反馈(Distributed Feedback, DFB)半导体激光器具有体积小、成本低和工艺成熟等优势，但兆赫兹量级的线宽使其应用范围受限。采用环形谐振器对其进行自注入锁定，可将线宽压窄到千赫兹量级，但仍存在锁定不稳定的问题。文章采用四只不同的环形谐振器对DFB半导体激光器进行自注入锁定，通过实验监测自注入锁定时多个端口的光功率、偏振态和光波长的变化，揭示影响DFB半导体激光器自注入锁定稳定性的因素有谐振模式跳变、偏振态跳变，以及外界温度和振动引起的锁定环路的相位变化，且使用不同类型的环形谐振器进行锁定时，主导的影响因素不同。控制这些影响因素可以改善DFB半导体激光器自注入锁定的稳定性，使DFB半导体激光器自注入锁定技术有更好的应用效果。

Analysis of Instability Factors of Self-injection Locking of DFB Semiconductor Laser

Distributed feedback (DFB) semiconductor lasers have the advantages of small size, low cost and mature manufacturing technology. However, their application scope is limited due to the MHz linewidth. The linewidth can be narrowed to the order of kHz by self-injection locking with ring resonators, but there exists instability as the laser being locked. We self-injection lock a DFB semiconductor laser to four different ring resonators and monitor the changes of optical power, polarization state and wavelength at multiple ports of the locking circuit. It is revealed that the factors affecting the locking stability of DFB semiconductor laser include resonant mode hopping, polarization state hopping, and phase change of the feedback locking loop caused by external temperature and vibration, and the dominant factors are different when different types of ring resonators are used. Control of these factors can improve the stability of the self-injection locking of DFB semiconductor lasers, so that better application effect can be achieved for the self-injection locked DFB semiconductor laser.