Design and performance of a cyclic fault-tolerant semiconductor optical amplifier switch matrix

We propose a cyclic fault-tolerant structure for a semiconductor optical amplifier (SOA) switch matrix in a tree arrangement by connecting the inputs of the switch matrix into a ring with additional SOAs. Upon component failures, the affected requests are rerouted through their neighboring inputs toward the desired outputs. By making use of the existing components while rerouting, the proposed structure achieves an excellent trade-off between the number of additional components, hence size and cost, and fault tolerance. Numerical simulations show that under 210 randomly distributed SOA failures in a 32 × 32 switch matrix, the proposed structure is still able to provide more than 99% connectivity between all input-output port pairs. We also show through simulations that the proposed structure could potentially scale up to large port counts by limiting the length of the rerouted paths. And its fault-tolerance capability improves as the size of the switch matrix increases. Experiments are conducted to verify the feasibility of the proposed structure. Our research provides clues to improve the fault tolerance of some kinds of switch matrices, where rerouting within the switch matrix itself is not possible, such as single-stage matrices.