Monolithic diffractive interference detector on silicon

The presented interference detector comprises a standard pn junction in a silicon substrate and a corrugation grating engraved at its surface. Two beams with unknown phase difference impinge onto the detector under the Littrow condition for some diffraction order of the grating. The detected power exhibits a non-zero AC component as the relative phase between the incident beams changes. The present paper describes the operation principle and brings the evidence of non-zero interference contrast in the application case of a displacement sensor.