We demonstrate stable single-frequency and polarization operation of a traveling-wave, Er3+-doped fiber loop laser by incorporating an unpumped Er3+-doped fiber section butted against a narrow-band feedback reflector. The saturable absorber acts as a narrow bandpass filter that automatically tracks the lasing wavelength, thus ensuring single-frequency 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 relative intensity noise was less than −112 dB/Hz at frequencies above 200 kHz and a laser linewidth of less than 0.95 kHz, whereas the lasing frequency was observed to drift slowly (∼170 MHz/h) because of environmental effects.
© 1995 Optical Society of America
Original Manuscript: October 24, 1994
Published: April 15, 1995
Y. Cheng, J. T. Kringlebotn, W. H. Loh, R. I. Laming, and D. N. Payne, "Stable single-frequency traveling-wave fiber loop laser with integral saturable-absorber-based tracking narrow-band filter," Opt. Lett. 20, 875-877 (1995)