C-band switchable multi-wavelength erbium-doped fiber laser based on Mach-Zehnder interferometer employing seven-core fiber

In this study, we propose and test a linear cavity erbium-doped fiber laser that incorporates a seven-core-based Mach-Zehnder interferometer (MZI). A 3.6-m-long erbium-doped fiber was selected as the gain medium. The all-fiber MZI was composed of two 105/125 μm multimode fibers and one seven-core fiber as the wavelength comb filter. A lasing threshold of 73 mW was used in the experiment, and a switchable laser with stable single and dual wavelengths was implemented by adjusting the polarization controller. In the experiment, five different single-wavelength lasers could be realized with power fluctuations lower than 0.98 dB within 10 min of scan time. In addition, five different dual-wavelength lasers could be obtained with a power shift lower than 1.09 dB at room temperature.