| Nonlinear Sagnac interferometer can be used in pulse shaping and noise reduction,all-optical logic operation and optical channel demultiplexing, etc.. Introducingnon-linear and magneto-optical effect of all-fiber Sagnac structure will have a goodprospect for application to the all-optical information processing, where nonlinearcoefficient and Verdet constant are two characterizing parameters. The research workincludes:1．The elliptical equation with pump depletion and fiber loss is derived fordegenerate four-wave mixing. The necessity of considering pump depletion and fiberloss is analyzed. The numerical results are consistent with Optisystem simulation data.The method proposed can be applied to the small signal case, but also to the process ofparametric saturation. This technique provides an important parameter for furtherdesigning the fiber-based2R regenerators.2．A method is presented to measure Verdet constant for magneto-optical fibersbased on Sagnac interferometer. The power-split ratio of the fiber coupler used inSagnac interferometer can be calculated from fiber loss and the minimum transmissivityavailable, and then effective Verdet constant is determined by the magnetic fielddependence of the transmissivity for Sagnac interferometer. By means of this method,the wavelength dependency of Verdet constant for a highly nonlinear fiber is alsomeasured, which is extremely useful for the study of magneto-optical four wave mixingassociated with magneto-optical coupling coefficient and operating wavelength.3． A new structure of all-fiber Sagnac interferometer with non-linear andmagneto-optical effects is proposed, in which the pump and the probe signals arecoupled into the Sagnac interferometer from external simultaneously. By Optisystemsimulation, the influence of the coupling coefficient and the applied magnetic field onthe power transfer function curve is analyzed, and the magnetic control characteristic ofthe nonlinear Sagnac interferometer is illustrated. |
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