Tunable dual-wavelength all-PM fiber ring laser

A multisegment all-PM fiber ring laser is constructed to demonstrate a tunable dual-wavelength laser source with continuous tuning in absolute wavelength and discrete tuning in wavelength spacing. The tuning method is based on birefringence filtering properties of a segmented all-PM fiber ring resonator. Using this method, we show a discrete wavelength spacing of dual-wavelength output from 0.9 to 2.5 nm, and continuous wavelength tuning over a few nanometers. The demonstrated dual-wavelength laser can be easily modified to tune over a greater wavelength spacing and absolute wavelength range.