Study of holographic grating in porous silicon optical waveguides

Abstract

It was found that the porosity of porous silicon has a maximum value under certain illumination intensity in our experiment. According to the experimental result, the grating was fabricated from porous silicon by controlling illumination intensity. As the refractive index of porous silicon decreases with an increase of the porosity, so the index distributing of porous silicon can be controlled by illumination intensity. A holographic process allows obtaining a mask of light on top layer during fabricating the multilayer porous silicon optical waveguides. The interference of two coherent Ar + laser beams produces at the sample surface bright parallel lines. The porosity is modulated in the plane. The effective deep of modulation is directly related to the penetration of the illuminating beam. We have developed an experimental setup that allows guide light at 1064nm incidents vertically into the grating in porous silicon optical waveguides. The diffractive efficiency of the first order diffraction light in TE and TM polarization are measured in our experiment respectively.