Influence of System Bandwidth on Self-mixing Signal

Self-mixing interferometry (SMI) is a well-developed sensing technology. An SMI system can be described using a model derived from the well-known Lang and Kobayashi equations by setting the system operating in stable region. The features of an SMI signal are determined by the external optical feedback factor (denoted by C). Our recent work shows that when the factor C increases to a certain value, e.g. in moderate feedback regime with 1<C<4.6, the SMI system might enter unstable region and the existing SMI model is invalid. In this case, the SMI signals exhibit some novel features and contain higher-frequency components. To detect an SMI signal without distortion or take suitable correction on the SMI signal, it is must to make an analysis on the system bandwidth and its influence on SMI signals The results in this paper provide useful guidance for developing an SMI sensing system.