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

We experimentally demonstrated a method of generating continuously wavelength-switchable LP
₁₁
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 LP
₁₁
mode can be output successfully. The experiment result shows that, the proposed fiber laser can operate at single-, dual-, triple- and quadruple-wavelength with LP
₁₁
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%).