Research Of All-Optical Switchings And Logic Gates Based On Nonlinear Of Fiber Bragg Grating

Nowadays we show great attention in Optical communication with the development of communication technology. All-optical signal processing involved high speed and huge capacity is required to the WDM (Wavelength Division Multiplexing) system. Varies of passive optical devices are used instead of expensive photoelectric conversion devices with the characteristics of low-cost and low-loss. Optical switching and logic gate appear to be a key component for all-optical signal processing as they are agile enough to cope with communication traffic. Fiber gratings attract attention among all-optical fields due to its tiny size for easy connection, low loss and mature manufacturing technology. Its nonlinear characteristics have also been widespread concern. All-optical switching and logic gate based on fiber Bragg gratings have a great potential to applications.In this paper, all-optical switching and. logic gate based on fiber Bragg gratings were studied. We discussed numerical studies of nonlinear coupled-mode equations, narrowband reflection characteristics and Ken-effects were observed when single continuous Wave and single pulse were input. Impacts on shape of output pulse with variation of pulse width were analyzed together with an improvement of extinction ratio. We also found the reduction of power threshold when considering pump light. We discussed different apodization function which affects switching performance, the parameters of Gauss-apodized were also concerned. The shape of the reflection spectrum and transmittance must be taken into account. Apodization was demonstrated to be helpful with improvement of switching stability. To investigate the improvement of nonlinear based on XPM, we brought out point defects. After the analysis of number and width of defects, the optimized scheme under the circumstance of FBG was demonstrated as power threshold valued11GW/cm2compared to27GW/cm2as before. The transmittance rises from40%to about98%. On the basis of a combination of all-optical switching, we design of a series of simple all-optical logic gates, such as "AND" gates and "OR" gates. We studied the phase shift of pulse peak during propagation affected by self-phase modulation and cross-phase modulation, and found an ideal value of pump power which lead to logic function. The output pulse had a nice shape. The research on fiber Bragg gratings was contributed to all-optical switching and logic gate devices.