Switchable multi-wavelength ytterbium-doped fiber laser based on a photonic crystal fiber Mach-Zehnder interferometer

In this work, a switchable multi-wavelength ytterbium-doped fiber laser (YDFL) based on a Mach-Zehnder interferometer (MZI) was experimentally demonstrated. The MZI was developed with a piece of photonic crystal fiber (PCF) between single-mode fiber (SMF) in a SMF-PCF-SMF configuration; in this way, it was used as a wavelength-selective filter (WSF) in the proposed ring cavity. The experimental results show that the YDFL can emit stable single, double, and triple wavelengths. The laser has a side-mode suppression ratio of approximately 51.68 dB and a narrow linewidth of 0.03 nm for its single-line emission. By changing the bending radius over the MZI with curvature from 0 to 3.33 m-1, we obtain a switchable wavelength behavior with possible lasing emission in the range of 1060.46–1073.52 nm. Furthermore, the system is compact, robust, and has a simple manufacturing process. •An in-line Mach-Zehnder fiber interferometer was implemented to mediate the active medium.•The curvature-sensitive filter enables the cavity to achieve switchable laser output.•Up to four different laser lines and triple simultaneous wavelengths were observed.•Highly stable output from a compact laser design and simple fabrication process.