Switchable and tunable multi-wavelength fiber laser based on a core-offset aluminum coated Mach-Zehnder interferometer

In this work, a switchable and tunable multi-wavelength erbium-doped fiber laser based on a core-offset aluminum coated Mach-Zehnder interferometer (ACMZI) is presented. The ACMZI is fabricated by core-offset fusion splicing a single-mode fiber segment between two lengths of single mode fiber and then by coating it with aluminum using the thermal evaporation technique. The ACMZI is used as a wavelength selective filter in the proposed ring cavity design. Experimental results show that the laser emission can be switched among a single, double, and triple emission lines by carefully adjusting a polarization controller. Furthermore, the laser lines can be tuned by changing the temperature of the ACMZI. The laser can emit in a single-longitudinal mode and has a single-mode suppression ratio of about 55 dB, a linewidth of 0.05 nm and an efficiency slope of 0.29%. Finally, the laser arrangement is compact, robust, and requires a relatively simple fabrication procedure.