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Spectrum-slicing provides a low-cost alternative to the use of multiple coherent lasers for wavelength division multiplexing (WDM) applications by utilizing spectral slices of a single broadband noise source for creating the multichannel system. In this paper we analyze the performance of both p-in and optical preamplifier receivers for spectrum-sliced WDM using actual noise distributions, and the results are compared with those using the Gaussian approximation. This extends prior results of Marcuse for the detection of deterministic signals in the presence of optical amplifier and receiver noise. Although the methodology is similar, the results are considerably different when the signal is itself noise-like. For the case of noise-like signals, it is shown that when an optical preamplifier receiver is used, there exists an optimum filter bandwidth which minimizes the detection sensitivity for a given error probability. Moreover the evaluated detection sensitivity, in photons/bit, represents an order of magnitude (>10 dB) improvement over conventional detection techniques that employ p-i-n receivers. The Gaussian approximation is shown to be overly conservative when dealing with small ratios of the receiver optical to electrical bandwidth, for both p-i-n and preamplifier receivers.

For the procedure of dispersion precompensation in fibers by prechirping, we found that there is a maximum distance over which a pulse initially compressed by prechirping can return to its original width. The distance constraint comes in the form of a mathematical relationship involving the distance, dispersion, initial pulse width, and peak power, implying that the restriction governs all the fiber parameters. Simple closed-form approximations for the constraint and for the corresponding required prechirp are derived on the basis of a variational approach. The validity of the analytical formulas is confirmed by split-step Fourier numerical simulation.