Công nghệ viễn thông điện tử đã tiếp tục tiến bộ nhanh chóng kể từ khi có phát minh hệ thống điện tín và điện thoại đến mức nó đã cách mạng hoá các phương tiện thông tin truyền thông | Analysis Design and Performance Evaluation of Optical Fiber Spectrum-Sliced WDM Systems by Vivek Arya Dr. Ira Jacobs Chairman Electrical Engineering ABSTRACT This dissertation investigates the design and performance issues of a recently demonstrated technique termed as spectrum-slicing for implementing wavelength-division-multiplexing WDM in optical fiber systems. Conventional WDM systems employ laser diodes operating at discrete wavelengths as carriers for the different data channels that are to be multiplexed. Spectrum-slicing provides an attractive low-cost alternative to the use of multiple coherent lasers for such WDM applications by utilizing spectral slices of a broadband noise source for the different data channels. The principal broadband noise source considered is the amplified spontaneous emission ASE noise from an optical amplifier. Each slice of the spectrum is actually a burst of noise that is modulated individually for a high capacity WDM system. The stochastic nature of the broadband source gives rise to excess intensity noise which results in a power penalty at the receiver. One way to minimize this penalty as proposed and analyzed for the first time in this work is to use an optical preamplifier receiver. It is shown that when an optical preamplifier receiver is used there exists an optimum filter bandwidth which optimizes the detection sensitivity minimizes the average number of photons bit for a given error probability. Moreover the evaluated detection sensitivity represents an order of magnitude 10 dB improvement over conventional PIN receiver-based detection techniques for such spectrum-sliced communication systems. The optimum is a consequence of signal energy fluctuations dominating at low values of the signal time bandwidth product m and the preamplifier ASE noise dominating at high values of m. Operation at the optimum bandwidth renders the channel error probability to be a strong function of the optical bandwidth thus providing motivation
