This paper examines wavelength translation in all-optical wavelength-routed networks. Previous studies [4-7] have shown that wavelength translation can improve the blocking performance of these networks. However, all previous work [4-7 has assumed that Wavelength t o any output wavelength. I n contrast, alloptical wavelength translators demonstrated in the laboratory t o date [9-111 are, in general, only capable of limited translation. I n this paper we assess, for the first time, the network performance improvements offered b y realistic all-optical wavelength translators with limited translation range. I n particular, we consider all-optical wavelength translators based on four-wave mixing in semiconductor optical amplifiers. Using a simple model f o r their function, we consider the blocking performance of two-hop and multiple-hop paths, and unidirectional ring and mesh-torus networks. In all the cases we consider, significant improvement in the blocking performance of the network is obtained when limited-range wavelength translators with as little as one quarter of the full range are introduced. We also find that almost all of the network performance improvement offered by an ideal wavelength translator can be gained from a translator with only half of the full translation range. wavelength translators can trans / ate f r o m any input

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We present a new steady-state frequency-domain model of highly nondegenerate four-wave mixing in bulk semiconductor optical amplifiers (SOA's). The model can handle a large number of interacting optical fields and situations in which the nonlinear interactions are complex. It accounts for the longitudinal dependence of the population inversion in the SOA and the spectral dependence of the gain. Carrier population pulsations, spectral-hole burning, and carrier heating, which dominate the nonlinear response over bandwidths into the terahertz range, are included. The model also includes output amplified spontaneous emission noise and allows important system parameters such as signal-to-noise ratio and noise figure to be estimated. A number of applications of the model are presented in which good agreement between theoretical and experimental results is demonstrated.Index Terms-Four-wave mixing, optical frequency conversion, semiconductor device modeling, semiconductor optical amplifiers, wavelength division multiplexing.

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