Patent ID: 6646747
Filing Date: 2003-11-11
Classification: B82Y,G02B,G02F,H01L

Abstract:
An optical interferometer, comprising:a beamsplitter that splits an input optical signal into a first optical signal that flows along a first optical path and a second optical signal that flows along a second optical path; a first mirror that reflects the first signal in the first path towards the beamsplitter to form a first return path; a second mirror that reflects the second signal in the second path towards the beamsplitter to form a second return path; a first delay element including the first mirror that adjusts a time required for the first signal to flow from the beamsplitter along the first path, be reflected by the first mirror, and return along the first return path to the beamsplitter, the delay element comprises: a waveguide that includes a region of changeable propagation constant disposed along a length of the waveguide, wherein the first optical signal is guided by total internal reflection in the waveguide, and the waveguide is formed at least in part from an active semiconductor; a first electrode positioned proximate a first surface of the region of changeable propagation constant and electrically separated from the active semiconductor; a second electrode in electrical contact with the active semiconductor and disposed on a first side of the region of changeable propagation constant; a two-dimensional electron (hole) gas (2DEG) having a free carrier distribution that is formed on the first surface of the active semiconductor when a voltage is applied between the first electrode and the second electrode; and wherein changing the voltage causes a corresponding change of the free carrier distribution which, in turn, causes corresponding change of a propagation constant level in the region of changeable propagation constant that changes the time required for light in the first optical signal to flow from the beamsplitter along the first path, be reflected by the first mirror, and return along the first return path to the beamsplitter.