A stable wavelength-spacing-tunable dual-wavelength single-longitudinal-mode fiber ring laser based on a DMD filter

A stable single-longitudinal-mode dual-wavelength( SLM-DW) multiple ring fiber laser with a tunable wavelength spacing was proposed and demonstrated. In the multiple ring cavities,the mode selection is made by the tunable digital micro-mirror device( DMD) filter and two different length passive sub-ring cavities. The DMD filter can select and couple any two wavelengths from the gain spectrum of the erbium-doped fiber( EDF). The SLM lasing is guaranteed by the two sub-ring cavities which serve as a mode filter. The stable and uniform dualwavelength oscillation is obtained by the highly-nonlinear photonic crystal fiber( HN-PCF),which can generate the four-wave-mixing( FWM) effective. By loading different gratings on the DMD filter without any mechanically shift,the tunable wavelength spacing from appropriately 0. 165 nm to 1. 08 nm within a tuning accuracy of 0. 055 nm is achieved at room temperature.