Stabilized single-frequency fiber ring laser based on hybrid amplifier and fiber Fabry-Perot devices for C- plus L-band operation

Abstract

Stabilized and tunable optical output are very necessary for fiber ring lasers applied to wavelength-division multiplexing (WDM) for communications and optical sensor systems. In general, a fiber Fabry-Perot (FFP) filter can provide wavelength tuning inside the ring cavity of the fiber ring laser. Because of the bandwidth limitation of erbium-doped fiber amplifiers (EDFAs), the operation region of erbium-doped fiber (EDF) ring lasers extends only from C to L band (1530 to 1610 nm)1- 2 and thus must be supplemented with the proposed S-band fiber ring laser.3 Actually, the wideband ring laser must use a long length of EDF even to approach C- plus L-band operation.1 However, that is insufficient to stabilize the lasing wavelength and power of a fiber ring laser. Recently, several remedial techniques, such as integrating two cascaded FFP filters of widely different free spectral ranges (FSRs) into a cavity,4- 5 using a compound ring resonator composed of a dual-coupler fiber ring and a tunable band pass filter,2 adding an extra ITU-grid periodic filter in the optical loop,6 and employing an integral saturable-absorber-based tracking narrowband filter,7 have been reported experimentally.