Standing wave detection and interferometer application using a photodiode thinner than optical wavelength

A thin film photodiode whose active layer is thinner than the wavelength of the incident light is described. A part of the incident photon is detected and the rest transmits through the thin film photodiode without absorption. Being inserted in the optical field, this sensor is applied to construct the new interferometer detecting the intensity profile of the standing wave of the thinnest interference fringe.