A monolithic optical displacement measurement microsystem

A monolithically integrated optical displacement measurement microsystem is presented. The microsystem consists of a Michelson interferometer with an integrated DBR laser and waveguide photodetector, fabricated on a single GaAs-based chip. Displacement measurements with sub-100 nm resolution have been performed, requiring only the alignment of the interferometer with an external lens for focusing the measurement beam. Obviating the need for alignment of the interferometer components implies that such an optical chip may be used for precision position or displacement measurement in movable MEMS or as part of a more complex semiconductor-based opto-mechanical microsystem.