Multi-wavelength erbium-doped fiber ring laser based on wavelength-dependent polarization rotation with a phase modulator and an in-line comb filter

A stable room-temperature multi-wavelength erbium-doped fiber ring laser has been proposed and investigated experimentally. A phase modulator composed of a piece of fiber wrapped around a cylindrical piezoelectric transducer is used to suppress the mode competition. And the combined action between optical fiber and polarization-dependent isolator provides the wavelength-dependent loss induced by wavelength-dependent polarization rotation mechanism to flatten the output spectrum, tune the locations and improve the number of the lasing lines. Stable multi-wavelength lasing with wavelengths up to 23 and the wavelength spacing of 0.4 nm is demonstrated. Moreover, the pulse train output was also observed.