Switchable and tunable multi-wavelength erbium-doped random distributed feedback fiber laser based on a compound filter

Abstract

A switchable and tunable multi-wavelength random distributed feedback fiber laser (RDFBFL) is realized based on the compound filter which is comprised of a dual-pass Mach-Zehnder interferometer (MZI) and a Sagnac loop mirror. The lasing threshold of the proposed RDFBFL is suppressed to 50 mW by the pumped erbium-doped fiber (EDF), and the pump efficiency is 1%. By simply adjusting the angle of polarization controller (PC) in the Sagnac loop, 2, 3, 5 and 6 lasing channels can be obtained under the pump power of 200 mW, and the central wavelengths of the 3 lasing channels can be simultaneously tuned with a fixed channel separation. Moreover, the power amplitudes and side mode suppression ratios (SMSRs) of lasing channels are maintained around − 10 dBm and 34 dB, respectively. The proposed RDFBFL has the advantages of ideal tunability and low threshold, which can be widely used in imaging systems and long-distance sensing.