Pump-induced, dual-frequency switching in a short-cavity, ytterbium-doped fiber laser.

Using a short linear cavity composed of a section of highly ytterbium-doped fiber surrounded by two fiber Bragg gratings, dual-frequency switching is achieved by tuning the pump power of the laser. The dual-frequency switching is generated by the thermal effects of the absorbed pump in the ytterbium-doped fiber. At each frequency, the laser shows single-longitudinal-mode behavior. In each single-mode regime, the optical signal-to-noise ratio of the laser is greater than 50 dB. The dual-frequency, switchable, fiber laser can be designed for various applications by the careful selection of the two gratings.