A tunable and single-frequency S-band erbium fiber laser with saturable-absorber-based autotracking filter

A method to achieve wavelength tunability and single-longitudinal-mode oscillation in an S-band erbium-doped fiber (EDF) ring laser is proposed and demonstrated. A saturable-absorber-based autotracking filter consisting of an unpumped EDF and an optical reflector is utilized to provide fine mode restriction and guarantee the single-frequency operation. The performance of output power of larger than 1 dBm, power stability of smaller than 0.02 dB, wavelength variation of less than 0.01 nm and side-mode suppression ratio of larger than 31 dB has been experimentally demonstrated for this single-frequency fiber laser operating from 1482 to 1512 nm.