STABLE SINGLE-FREQUENCY TRAVELING-WAVE FIBER LOOP LASER WITH INTEGRALSATURABLE-ABSORBER-BASED TRACKING NARROW-BAND-FILTER

We demonstrate stable single-frequency and polarization operation of a traveling-wave, Er3+-doped fiber loop laser by incorporating an unpum ped Er3+-doped fiber section butted against a narrow-band feedback ref lector. The saturable absorber acts as a narrow bandpass filter that a utomatically tracks the lasing wavelength, thus ensuring single-freque ncy operation. Output powers up to 6.2 mW at 1535 nm were obtained for launched pump powers of 175 mW at 1064 nm. At this output, the relati ve intensity noise was less than -112 dB/Hz at frequencies above 200 k Hz and a laser linewidth of less than 0.95 kHz, whereas the lasing fre quency was observed to drift slowly (similar to 170 MHz/h) because of environmental effects.