Novel all-optical planar and compact minimum-stage switches of size > or = 4*4

Throughout the paper, novel all-optical planar 1-stage k*k-switches and compact minimum-stage k*k-switches in double-layer and multi-layer technique, are presented and analysed. In the first case, the number of k(k-1)/2 switches of size 2*2 ( identical to minimum of the Spanke-Benes network) are arranged in parallel instead of the number of k ( identical to maximum) cascaded 2*2-switches of the Spanke-Benes network. In the second case, the number of 2*2-switches depends on the geometry of the 'pipes' of the switches formed by the layers and waveguides [for a square it is 3k/2(k/2-1) for rearrangeable nonblocking and 3(k-1)k/2(k/2-1) for circuit switching networks]. The number of stages (NS) (horizontal cascaded) of the proposed compact switches for the nonblocking interconnection is NS=n.1 if the waveguides form an n.gon (n>or=3) for any size of the k*k-switch. In this way, the attenuation of optical signals passing through a photonic network may be minimized. In particular, for any size of a k*k-switch, dependent on the n-gon, the minimum NS is n-1=2 (triangle) or n-1=3 (square), etc. Thus the proposed switch concept is of complexity O(1), i.e. The NS is independent of the number of inputs/outputs. Additionally, the proposed switches are capable to operate in the circuit switching mode if and only if (iff) the parallelism increases by the factor k-1.