Stable multi-wavelength PM-EDF linear cavity laser employing a TCF fiber comb filter and an SNOLM

Abstract

We propose and demonstrate a stable multi-wavelength polarization-maintaining erbium-doped fiber (PM-EDF) linear cavity laser by using a twin-core fiber (TCF) comb filter and a symmetric nonlinear optical loop mirror (SNOLM). Using a homemade TCF, we fabricate a TCF comb filter with a channel spacing of 0.29 nm. By adjusting the polarization controllers (PCs) carefully, the polarization hole-burning effect in the PM-EDF is enhanced and intensity-dependent loss is produced by a nonlinear polarization rotation effect in the SNOLM. As a result, the homogeneous broadening gain medium is effectively reduced, and the mode competition of the EDF is distinctly suppressed. With only 100 mW pump power, up to 52-wavelength stable outputs with channel spacing of 0.29 nm have been achieved at room temperature. The power fluctuation and wavelength shift for each lasing wavelength are less than 0.1 dB and 0.02 nm in an hour, respectively. Experimental results illustrate that the proposed structure of a fiber laser can realize multi-wavelength outputs with high stability at lower pump power.