Triple-wavelength Switchable Multiwavelength Erbium-doped Fiber LaserBased on a Highly Nonlinear Photonic Crystal Fiber

摘要

We propose and experimentally investigate a novel scheme for a triple-wavelength switchable multiwavelength erbium-doped fiber laser based on a highly nonlinear photonic crystal fiber incor-porating a multiply-phase-shifted fiber Bragg grating. A nonlinear optical loop mirror based on a highly nonlinear photonic crystal fiber is exploited to suppress the homogeneous line broadening of an erbium-doped fiber amplifier and to provide the triple lasing wavelength switchability. A multiply-phase-shifted fiber Bragg grating with three channels, depending on the number of phase-shifted segments, is implemented to establish a multichannel filter and to generate the multiwavelength output. A high-quality multiwavelength output with a high extinction ratio of ~45 dB and a high output flatness of~0.3 dB is realized. The switching performance to provide lasing-wavelength selectivity can be realized by using a nonlinear polarization rotation based on a nonlinear optical loop mirror. The lasing wavelength can be switched individually by controlling both the polarization controller within the nonlinear optical loop mirror and the cavity loss. The proposed multiwavelength fiber laser can be operated in the single-, dual-, and triple-lasing wavelength states. Based on the bending technique, the lasing wavelength of the proposed multiwavelength erbium-doped fiber laser can be readily controlled, and its tunability was measured to be~7.2 nm/m~(-1).