High-speed Optical Fiber Communication Systems, Cross-phase Modulation Effect

The fiber-optic systems are developing into wide-band fiber-optic communication systems with huge capacity. As the most widely used method in the backbone communication networks, dense wavelength division multiplexing (DWDM) technology has made remarkable progress. With the increase of the input power and the reduction of the channel separation, nonlinear effects, which has been ignored in the low-bit rate linear systems, has distinguished itself and can not be neglected any more. This work mainly studies the influence of cross phase modulation (XPM) on DWDM systems and schemes to suppress the influence. In addition, all-optical wavelength converter based on XPM in optical fiber is studied. First the commonly used algorithms-Split-step Fourier Method and its enhancement are introduced, as well as the simulation platform mainly used in this work-VPITransmissionmaker by VPI (With its former name PTDS, Photonic Transmission Design Suite). Then the optimal design of a single 40Gbps system and the influence of the dispersion compensation on systems are given. XPM is the mainly considered nonlinear effects in high-speed WDM systems. With dispersion, XPM can induce intensity fluctuations and timing jitter of the pulses in the receiver. It can also cause the spectral spreading of the channel so that crosstalk is introduced. All these effects put a tight limit on the capacity of the systems. In chapter 3, XPM is intensively studied. First, the mean field method is studied in WDM systems with different dispersion maps. By employing this method the computational complexity is greatly reduced without significant sacrifice of the accuracy of the results. Then the filter model is deduced to describe the intensity fluctuation induced by XPM in dispersion managed systems. According to this model, optimal dispersion management schemes are got. The amplitude fluctuation and according system performance degradation induced by XPM is also studied through numerical simulation. The timing jitter caused by XPM can also have great impact on system performance. By employing Lagrangian variational method and statistical method, the timing jitter caused by XPM in strong dispersion managed RZ systems is studied in chapter 3.Although XPM can cause system performance degradation, it finds significant applications in all-optical high speed signal processing, since its response time is veryshort. A kind of wavelength converter based on XPM in dispersion shifted fiber(DSF) is studied in chapter 4, where the critical parameters and their influence on the performance of the wavelength converter are studied.