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 co nsists of a distributed Bragg reflector laser, two photodetectors, two phase modulators, two Y-couplers, and two directional couplers. Tt is configured as a double Michelson interferometer and allows the determ ination of both magnitude and direction of a displacement. The detecti on of two 90 degrees phase-shifted interferometer signals also resulte d in an improved phase interpolation of phi/20, Despite tile relativel y simple fabrication process, the integration of rather complex optica l functions could be realized.