Duplex self-mixing interference based on ultra-narrow linewidth fiber ring laser

A novel duplex self-mixing interference based on ultra-narrow linewidth fiber ring laser is investigated. Dense Wavelength Division Multiplexing (DWDM) is applied to add-drop the dual-channel vibration signal into the fiber laser. Meanwhile, the output power with optical feedback is theoretically deduced which can not only be interpreted by the well known expression of self-mixing interference but the combination of self-mixing interference and mode competition. Experimental results show that different movements of each channel detected from the dual-channel fiber laser self-mixing interference system are in good agreement with theoretical analysis. Furthermore, a novel system measuring 2-dimensional vibration is introduced in this paper and its potential application to self-mixing interference measurement system for high sensitivity, remote and multi-dimensional measurement is shown.