Multi-Wavelength Fiber Laser Based on Dual-Sagnac Comb Filter for LP11 Modes Output

We experimentally demonstrate a multi-wavelength fiber laser based on dual-Sagnac comb filter with LP11 modes output. The filter is used to generate comb spectrum, which is consisted of three optical couplers, two polarization controllers and two segments of polarizationmaintaining fibers. The proposed fiber laser can stably output up to quintuple-wavelength with the side-mode-suppression ratio higher than 40 dB. Sextuple-wavelength lasing is also obtained, but due to the strong mode competition, the stability should be further improved. A mode selective coupler (MSC) is utilized as mode converter in the cavity. Thus, the multi-wavelength LP11 modes is feasible to generate, owing to the combination of MSC and the filter. The mode purity of the output LP11 modes is higher than 95%. This work has potential applications in optical communication and optical sensing system.