Self-mixing interference in fiber ring laser and its application for vibration measurement

A new approach for self-mixing interference in fiber ring laser and its application to vibration measurement is presented. Fourier transform method is proposed to improve the measurement accuracy of such an active sensing, in which the basic frequency of self-mixing interference signal is used to determine the frequency of vibration, and the stop order of the harmonic components is proportional to the amplitude of vibration. We have demonstrated this system to measure the microscopic vibration of a remote target. Some errors due to this method are discussed. The maximum error of the amplitude is about lambda/10 and the maximum error of the frequency is about 10%, showing a good agreement with the simulative results.