Comparative study of Raman fiber laser in symmetrical and asymmetrical cavities.

We propose and demonstrate a novel technique to generate a stable multiwavelength Raman fiber laser (RFL) based on an asymmetrical all-fiber Raman laser cavity by using a wideband chirped fiber Bragg grating (CFBG). The wideband CFBG as an input reflector has a high reflectivity covering the spectral range from 1402 to 1463 nm. Output couplers are composed of three discrete fiber Bragg gratings (FBGs), which generate a multiwavelength laser with center wavelengths of 1415, 1430, and 1445 nm. The output power variations from detuning the center wavelengths of the in-out reflectors are compared experimentally and theoretically in symmetrical and asymmetrical cavities. It is shown that the RFL output with an asymmetric cavity is more stable than that of a symmetric cavity. [ABSTRACT FROM AUTHOR]