Fiber Ring Laser Employing an All-Polarization-Maintaining Loop Periodic Filter

A novel erbium-doped fiber ring laser employing an all-polarization-maintaining fiber birefringent loop as a periodic filter is proposed and demonstrated. The laser using 1 nm interval filter generates four wavelengths with equal frequency spacing without using any techniques to overcome the homogeneous line broadening of the gain medium at room temperature. Room-temperature operation of dual-wavelengths with 0.56 nm spacing has also been realized.