CW stimulated Brillouin scattering in optical fiber: new insights into fundamentals and applications of the phenomenon

A series of new features of SBS have been observed experimentally. Among these, spectral hole burning, massive waveguide induced spectral broadening of the Stokes and abnormally small broadening of the transmitted pump radiation and, not least, the occurrence of DC Stokes emission. It was observed that, SBS spectrum, rather then being homogeneous in accordance with classical understanding, is in fact inhomogeneous. It was shown that this new phenomenon is a generic property of stimulated scattering in fibers, deriving from the ability of such media to guide a fan of beam directions. SBS was also found to exhibit spectral self-phase conjugation (SpSPC), a phenomenon which is the direct consequence of multi-frequency SBS interaction. Such phenomenon has resolved the serious problem of why SBS, generated from spontaneous Brillouin scattering, exhibits stable DC rather than fully stochastic Stokes emission, as expected from classical theory.