Widely tunable ring-cavity tellurite fiber Raman laser

We report a widely tunable ring-cavity tellurite fiber Raman laser covering the S+C+L+U band. Atunable range (1495-1600 nm, limited by the tunable optical bandpass filter) over 100 nm is obtained by using a single-mode tellurite fiber with high Raman gain coefficients (55 W-1 km(-1)) and large Raman shift (similar to 22.3 THz) as the gain medium. Furthermore, the free-running 1665 nm Raman fiber laser is achieved from the ring cavity by removing the tunable optical bandpass filter, which shows that such a tellurite fiber has potential for constructing a widely tunable fiber Raman laSEr covering the S+C+L+U band. A high optical signal-to-noise ratio of over 60 dB for almost all of the tunable range is also demonstrated. (c) 2008 Optical Society of America.