Analysis of the sensitivity of a monolithic optical phase-shift detector to geometrical parameter variations

Modelling of a novel monolithic optical phase-shift detector is presented. The device consists of a diffraction grating etched at the surface of a p-n photodiode on silicon. The photodiode generates a current depending on the relative phase between two incident beams collimated toward the diffraction grating. It is shown that the photocurrent contrast, given by the whole range of the phase variation, can be optimised by a precise determination of the period, depth and filling factor of the grating. Detailed analysis of the device performance for TE and TM polarization shows its high sensitivity to the above geometrical parameter variations.