Patent ID: 6222955
Filing Date: 2001-04-24
Classification: G02B,G02F,H04Q

Abstract:
An optical switch for routing a beam of light from a first input port to a selected output port, the optical switch comprising:a Z.times.T optical switch having Z input ports including the first input port and T output ports;an integrated optical Mach-Zehnder interferometer comprising a first N.times.N multimode interference coupler having N input ports and N output waveguides, at least two of the N input ports coupled to at least two of the T output ports of the Z.times.T optical switch, and a second N.times.N multimode interference coupler having N output ports including the selected output port and N input waveguides, wherein N output waveguides of the first N.times.N multimode interference coupler are optically coupled with N input waveguides of the second N.times.N multimode interference coupler thereby forming N waveguide arms; andan optical path length changer for changing an optical path length of at least one of the N waveguide arms,wherein N is an even value greater than 3, and T is at least 2, such that the beam of light is launched into the first input port and emerges substantially from the selected output port.