SINGLE-LONGITUDINAL-MODE FIBER LASER WITH A PASSIVE MULTIPLE-RING CAVITY AND ITS APPLICATION FOR VIDEO TRANSMISSION

A single-longitudinal-mode erbium-doped fiber laser with a passive mul tiple-ring cavity (MRC) is proposed for the first time to the authors' knowledge. The laser is fundamentally structured by insertion of thre e different short ring cavities, which serve as mode filters, into the main cavity. When it is combined with a mode-restricting intracavity fiber Bragg grating, the MRC resonator ensures single-longitundinal-mo de laser oscillation. The laser can successfully suppress side-mode fr equencies of as much as 1 GHz and provide an output power of 23 mW wit h a side-mode suppression ratio of 51 dB at 1533 nm. The short-term li newidth of the laser output measured is similar to 2 kHz. The ability of this fiber laser to act as an AM transmitter source is also demonst rated. (C) 1998 Optical Society of America.