Patent ID: 6915032

Claim:
A method of controlling an optical crosspoint switch which comprises intersecting input and output waveguides forming an intersection, a first upper active waveguide portion which is arranged adjacent to the input waveguide and which extends at least partially along the input waveguide to the intersection, a second upper active waveguide portion which is arranged adjacent to the output waveguide and which extends at least partially along the output waveguide from the intersection, and a corner mirror located at the intersection for coupling light signals from the first upper active waveguide portion to the second upper active waveguide portion wherein both refractive index and optical gain/loss of each active wavequide portion are changed by application of an electrical signal, the method comprising the steps of: in an OFF state of the switch, using an electrical signal varying the refractive index profile of the first and second upper active waveguide portion in order to prevent light transfer from occurring between the first and second upper active waveguide portion and the input and output waveguides respectively; and in the OFF state of the switch, using the electrical signal varying the optical gain/loss characteristics of first and second upper active waveguide portions, thereby enhancing the prevention of light transfer between the first and second upper active waveguide portions and the input and output waveguides respectively.