A monolithically integrated double Michelson interferometer for optical displacement measurement with direction determination

A monolithically integrated optical displacement sensor fabricated in the GaAs-AlGaAs material system is reported. The single-chip device consists of a distributed Bragg reflector laser, two photodetectors, two phase modulators, two Y-couplers, and two directional couplers. It is configured as a double Michelson interferometer and allows the determination of both magnitude and direction of a displacement. The detection of two 90/spl deg/ phase-shifted interferometer signals also resulted in on improved phase interpolation of o/20. Despite the relatively simple fabrication process, the integration of rather complex optical functions could be realized.