Random Laser With Multiphase-Shifted Bragg Grating in Er/Yb-Codoped Fiber

A random fiber laser is demonstrated based on a 25-mm-long multiphase-shifted fiber Bragg grating fabricated in a highly Er/Yb-codoped fiber with the beam-scanning method. By inserting 20 phase errors with random amplitudes along the grating length and pumping it with a 980-nm laser diode, we achieved random laser output with high-optical signal-to-noise ratio up to 65 dB. The laser can be operated at either single- or dual-wavelength modes with changeable lasing wavelengths depending on the power of pump laser. The pump threshold is only 28 mW, and the output stability is greatly improved by immersing the active fiber in water. It is, to the best of our knowledge, the shortest random fiber laser reported so far, if only the effective part of the fiber is considered.