Bistability-Mapping for$L$-Band Dual-Wavelength Erbium-Doped Fiber Laser by Using Fiber Loop Mirror With Polarization Controller

A novel technique to map the optical bistability and to switch the wavelengths of an L-band dual-wavelength erbium-doped fiber laser is present. By inserting a polarization controller (PC) into a fiber loop mirror (FLM) based on a 3-dB fiber coupler, the FLM reflectivity can be adjusted with the PC. When the FLM is used as the common reflector of the laser, the bistability of the laser can be controlled to vary monotonically with the FLM reflectivity. Based on this property, the bistability and the dual-wavelength of the laser may be respectively mapped and switched with respect to each other by adjusting the PC for any pump when it is between the first turning point of the bistability for maximum FLM reflectivity and the second turning point of the bistability for minimum FLM reflectivity