The study of internal cavity optical feedback effect in fiber linear lasers

In this paper, an internal cavity optical feedback system is presented based on the structure of fiber linear lasers. As the effects of optical feedback could be equivalent to the variation of laser cavity loss, we deduced the output variation equation of the optical feedback system. The output characteristics obtained by simulation and experiment observation are similar to the characteristics of self-mixing interference effect in semiconductor lasers. The similarity indicates the former system presented in this paper can be used in active sensing applications, such as displacement, reflectivity, and distance measurement.