Diffraction Grating for an Integrated CMOS-Compatible Optical Phase-Shift Sensor

Design of a diffraction grating for an integrated CMOS-compatible optical phase-shift sensor and corresponding validation test are presented. The sensor consists of a diffraction grating etched at the surface of a p-n photodiode. The photodiode generates a current depending on the relative phase between two incident beams collimated toward the diffraction grating. For a given incidence condition, the geometrical parameters of the grating are determined to optimize the photocurrent contrast. Experimental devices are tested exhibiting performances in good match with the theoretical analysis.