Wavelength-Switchable Fiber Laser Based on Mach-Zehnder Filter With LP11 Mode Output

We experimentally demonstrated a method of generating continuously wavelength-switchable LP11 mode in an all-fiber laser. A Mach-Zehnder filter is constructed to provide a comb spectrum. A fused mode selective coupler (MSC) is used to obtain mode conversion and LP11 mode can be output successfully. The experiment result shows that, the proposed fiber laser can operate at single-, dual-, triple- and quadruple-wavelength with LP11 modes output by adjusting the polarization controllers (PCs). The wavelength ranges are adjustable, when the output of the proposed fiber laser are single-, dual-, and triple-wavelength. Besides, the interval of dual wavelengths is also adjustable to some extent. Due to the superior characteristics of the Mach-Zehnder filter and the MSC, the proposed wavelength-switchable fiber laser has the merits of good stability, high signal-to-noise ratio (SNR, higher than 36 dB) and high mode purity (high to 95%).