Room-temperature switchable triple-wavelength operation of an erbium-doped fiber laser

A switchable triple-wavelength erbium-doped fiber laser employing a linear cavity incorporating a spatial mode beating filter was proposed and demonstrated. The filter formed by the incorporation of a section of multimode fiber into a single-mode fiber loop mirror was used as a comb to select lasing wavelengths. By using a polarization controller and spatial hole-burning effect, this laser could switch to output single wavelength, dual wavelength and triple wavelength in the C- plus L-bands at room temperature. The laser, with an optical signal-to-noise ratio of more than 45 dB and wavelength spacing of 2 nm, had good power uniformity and stability.