Switchable multi-wavelength erbium-doped photonic crystal fiber laser based on nonlinear polarization rotation

Abstract

A multi-wavelength erbium-doped photonic crystal fiber (ED-PCF) ring laser based on nonlinear polarization rotation was demonstrated experimentally. To the best of our knowledge, this study is the first to use a polarization-dependent isolator with an ED-PCF to form an equivalent fiber filter. The intensity-dependent inhomogeneous loss induced by nonlinear polarization rotation was applied to reduce the mode competition caused by ED-PCF. A detailed theoretical analysis using the Jones matrix method to calculate the transfer function of the laser was presented. The theoretical data, which were confirmed by the experimental results, showed that a multi-wavelength with a spacing of approximately 2.26nm was achieved by controlling the polarization controller. The proposed fiber laser with a signal-to-noise ratio higher than 40dB achieved a low threshold power of 30mW. Therefore, stable multi-wavelength outputs with a power fluctuation of less than 2dB were generated at room temperature.