Self-mixing dual-frequency laser Doppler velocimeter

摘要

Self-mixing laser Doppler velocimeter (SM-LDV) using semiconductor lasers is a well-established technique for velocity measurement. It has the advantages of simple and compact setup, good sensitivity and direction dis-criminability [1]. However, being a coherent detection scheme, SM-LDV also encounters the similar problems in the conventional single-frequency LDV (SF-LDV) where the velocity resolution is significantly reduced due to the inherent phase noise of the optical field and the speckle noise generated by the diffused target [2,3]. In our previous research, we have proposed a dual-frequency LDV (DF-LDV) that transmits the light-carried microwave to probe the target for coherence enhancement and speckle noise reduction [4]. In this study, we further demonstrate a self-mixing dual-frequency LDV (SM DF-LDV) for integrating both the advantages of the SM-LDV and DF-LDV based on the hybrid dynamics of a diode laser subject to both optical injection and optical feedback.