Switchable single-longitudinal-mode dual-wavelength erbium-doped fiber laser based on one polarization-maintaining fiber Bragg grating in linear cavity

Abstract

Switchable single-longitudinal-mode (SLM) dual-wavelength erbium-doped fiber laser at room temperature is demonstrated. One fiber Bragg grating (FBG) directly written in a polarization-maintaining and photosensitive erbium-doped fiber as the wavelength-selective component is used in a linear laser cavity. Because of the polarization hole burning enhanced by the polarization-maintaining FBG, the laser can be designed to operate in stable dual-wavelength or wavelength-switching modes with a wavelength spacing of 0.202 nm by adjusting a polarization controller. The stable SLM operation is guaranteed by a saturable absorber. The optical signal-to-noise ratio of the laser is >40 dB. The amplitude variation in nearly 1.5 h is <0.5 dB for both wavelengths.