Dynamic Stability Analysis for a Self Mixing Interferometry

In recent years, as an emerging and promising non-contact sensing technique, Self Mixing Interferomerty (SMI) has attracted much attention of researchers. The SMI is based on the self-mixing effect that occurs when a small fraction of laser light emitted by the semiconductor laser (SL) is reflected by an external target and re-enters the SL cavity. Therefore, the core components of an SMI consist of an SL, a micro-lens and a target. The target forms an external cavity for the laser, and when it moves along the light beam, a modulation in the emitted laser power can be observed. This modulated power is referred to as an SMI signal which carries the information of the motion of the target as well as the SL itself. Compared to other traditional interferometric schemes, e.g., Michelson or Mach-Zender, SMI has the advantages of a compact set-up, high sensitivity and low cost.