US Patent 9091747 Self-mixing interference device with wave guide structure

The proposed self-mixing interference device comprises a substrate (1) with an integrated optical wave guide structure (3), a semiconductor laser source (2) arranged on a surface of the substrate (1) and emitting laser radiation towards said surface, and a photodetector arranged to detect intensity variations of the laser radiation. The wave guide structure (3) is optically connected to the laser source (2) and designed to guide the laser radiation emitted by the laser source to an out-coupling area at the surface of the substrate (1) and to guide a portion of the laser radiation scattered back from a target object (4) outside of the substrate (1) to re-enter the laser source (2). This self-mixing interference device can be realized with a lower total height compared to the known self-mixing interference devices.