自注入锁定DFB半导体激光器用作φ-OTDR光源研究

Study on Self-Injected Locked DFB Semiconductor Laser as φ-OTDR Light Source

φ-OTDR分布式振动传感系统需使用窄线宽和频率漂移率小的相干光源,DFB半导体激光器的线宽通常在MHz量级且频率稳定性差,无法直接用作φ-OTDR系统的光源。本文使用光纤环形谐振器利用自注入锁定的方法来压窄DFB半导体激光器的线宽并稳定其频率,并且将其作为φ-OTDR分布式振动传感系统的光源。自注入锁定实现了约300倍的线宽压窄,振动传感实验显示该系统有时能测到振动信号有时不能,表明锁定过程中的跳模是自注入锁定激光器用于φ-OTDR振动传感系统时需要克服的困难。

A coherent light source with narrowlinewidth and small frequency drift rate is needed for an φ-OTDR distributed vibration sensing system. The linewidth of the DFBsemiconductor laser is usually in the order of MHz and its frequency stabilityis poor, so it cannot be used directly as a light source for an φ-OTDR system. In this paper, a fiberring resonator is used to narrow the linewidth and stabilize the frequency of aDFB semiconductor laser by using the self-injection locking method, and thelaser is used as the light source of an φ-OTDRdistributed vibration sensing system. The self-injection locking can achieveabout 300-time narrowing. The vibration sensing experiment shows that the systemcan sometimes distinguish vibration signals and sometimes cannot. Wedemonstrate that the mode hopping in the locking process is a difficulty to beovercome when the self-injection locking laser is used in the φ-OTDR vibration sensing system.