Wavelength switchable erbium-doped fiber laser incorporated with polarization maintaining photonics crystal fiber based Lyot filter

In the paper, an erbium doped fiber laser (EDFL) based on Lyot comb filter for wavelength switchable laser generation was proposed and demonstrated. For the designed fiber laser, Lyot filter was fabricated by insert a 0.5 m length polarization maintaining photonic crystal fiber (PM-PCF) into ring cavity, and free spectral range was 3.3 nm. In the experiment, the 4 m length EDF was used as EDFL gain medium, and pump power was 38 mW. When pump power was 140 mW, for 1527.7 nm single wavelength laser, the signal-to-noise ratio (SNR) was 22 dB, and 3dB linewidth was 0.05 nm. Through adjusting polarization controller (PC), the single-wavelength switchable laser tuned from 1525.73 to 1534.07 nm was realized, the wavelength tuning spacing was more than 1.99 nm, and power shift was less than 2.92 dB. For the proposed EDFL, switchable dual-wavelength laser was realized, or triple- and quadruple-wavelength laser output could be obtained respectively by adjusting PC. The power stability for single and dual-wavelength lasers were less than 0.702 and 1.452 dB respectively during 25 min monitoring time.