Wavelength tunable erbium-doped fiber laser based on all-fiber bitaper Mach-Zehnder interferometer incorporating photonic crystal fiber in ring cavity

The wavelength-switchable and stable erbium-doped fiber laser (EDFL) based on a Mach-Zehnder interferometer (MZI) was designed and experimentally demonstrated. For the proposed fiber laser, a bitaper MZI was manufactured using extrusion splicing photonics crystal fiber (PCF) and single-mode fiber to generate the comb filter effect. In the experiment, an erbium-doped fiber with a length of 3 m was used as the laser gain medium in the cavity. The laser threshold was 95 mW, and a laser output of 1563.06 nm was obtained. Single-wavelength tunable lasing from 1561.22 to 1563.34 nm with a minimum tuning space of 0.08 nm was realized. The power fluctuation was lower than 3.261 dB, and the signal-to-noise ratio (SNR) exceeded 28.535 dB. By tuning the polarization conditions, dual-, triple-, and quadruple-wavelength lasers with power fluctuations lower than 0.23, 2.94, 6.77 dB, respectively, were realized in the experiment. The 3 dB linewidth for the laser was less than 0.06 nm. The results indicate that single-, dual-, triple-, and quadruple-wavelength-tunable lasers can be realized using the proposed fiber laser.