All-fiber self-mixing laser Doppler velocimetry with much less than 0.1 pW optical feedback based on adjustable gain
Yuanyang Zhao, Desheng Zhu, Youze Chen, Yourui Tu, Tiezhu Bi, Yunkun Zhao, Benli Yu, Liang Lü
Abstract
The all-fiber self-mixing laser Doppler velocimetry with adjustable gain is experimentally investigated based on a distributed Bragg reflector fiber laser. In the measurement system, the modulation gain of the injected light in the laser cavity is adjusted by a pair of fiber-coupled acousto-optic modulators (AOMs) in the external cavity, which can change the intensity and frequency of the self-mixing modulation effect. Simultaneously, the minimum feedback intensity from the target to the laser for successful measurements is 0.063 pW. Thus, the all-fiber laser velocimetry can adapt to the detection of ultraweak optical feedback and wide-range velocity measurements in various complex scenes.