Multiwavelength erbium-doped fiber laser based on a nonlinear amplified loop mirror with a highly-nonlinear photonic crystal fiber

Abstract

A multiwavelength erbium-doped fiber laser based on a nonlinear amplified loop mirror with a highly-nonlinear photonic crystal fiber was proposed and experimentally investigated. The performance of the nonlinear amplified loop mirror was improved by using a single 3-dB coupler and a highly-nonlinear photonic crystal fiber with a length of 100 m. The extinction ratio of the proposed multiwavelength erbium-doped fiber laser was measured to be more than 50 dB. The output power fluctuation was measured to be less than 0.5 dB. The output power difference among multiple peaks was measured to be less than 0.3 dB. A Lyot-Sagnac filter with two segments of polarizationmaintaining photonic-crystal fibers was employed as a multichannel filter, and the wavelength spacing was controlled by changing the polarization states within the Lyot-Sagnac filter. Two different wavelength spacings, 0.6 nm and 0.8 nm, were obtained. The number of channels was also changed: 20 for Δλ = 0.6 nm and 16 for Δλ = 0.8 nm. In addition, a precisely-interleaved switching based on the proposed multiwavelength erbium-doped fiber laser was realized by changing the polarization states.