Abstract: In this work we present an optical network architecture and deflection (or hot potato) routing algorithms supporting efficient communication between n processor nodes in a shared memory parallel computer. The sparse optical torus network consists of an n x n torus, where processor nodes are situated diagonally, and routing nodes are optical deflection nodes of two inputs and two outputs. A design of optical deflection node is presented. Several routing algorithms, based on the greedy routing algorithm, are developed. By experiments and partial theoretical analyses these algorithms run efficiently on sparse optical torus.