Optimization of Bistability in Nonlinear Chalcogenide Fiber Bragg Grating For All Optical Switch and Memory Applications

We solve the coupled mode equations governing the chalcogenide nonlinear fiber bragg gratings (fbgs) numerically, and obtain the bistability characteristics. the characteristics of the chalcogenide nonlinear fbgs such as: switching threshold intensity, bistability interval and onoff switching ratio are studied. the effects of fbg length and its third order nonlinear refractive index on fbg characteristics are investigated. we obtain an interesting result that independent of the third order nonlinear refractive index; there exists an optimum fbg length of about 6 mm at which the onoff switching ratio becomes maximized. it is also found that by increasing the nonlinearity, the maximum value of onoff switching ratio decreases. the results of this paper can be mainly used for designing alloptical switches and memories.