Patent ID: 7424181

Claim:
An optical device comprising: a first and a second splitting device, each of the first and second splitting device having respective first and second input port, respective first and second output port and a respective transfer matrix; a first optical waveguide optically coupling the first output port of the first splitting device and the first input port of the second splitting device; and a second optical waveguide optically coupling the second output port of the first splitting device and the second input port of the second splitting device; wherein the first and second optical waveguide are configured to introduce a phase shift of radians to the optical radiation propagating through the first optical waveguide with respect to the optical radiation propagating through the second optical waveguide, said transfer matrix of the second splitting device is the diagonal transpose of the transfer matrix of the first splitting device and the transfer matrix of the second splitting device is substantially different from the transfer matrix of the first splitting device.