Optical communications with photonic switching are promising to provide high bandwidth and low error bit. Self-routing strictly nonblocking networks are always favoured to be used as switching networks due to their simple routing mechanisms and nonblocking properties. However, crosstalk problems in photonic switching add a new dimension of nonblocking constraints on optical switching networks. The classical self-routing strictly nonblocking N × N crossbar network has i N~2 switching elements (SEs) and 2N - 1 connection diameter, and needs N wavelengths for nonblocking switching. In this paper, we propose a new class of self-routing strictly nonblocking networks by studying the connection capacity of self-routing blocking Banyan-type networks. The new proposed N × N networks have no more than N~2 - N SEs and (log N) connection diameter. Furthermore, they need no more than two wavelengths for nonblocking switching. Compared with existing strictly non-blocking self-routing networks, the presented new networks have lower hardware cost, shorter connection diameter, and much smaller number of required wavelengths. Consequently, they are more feasible for implementation with reduced optical signal attenuation and crosstalk.
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