Diffraction grating formation on porous silicon using a CO2 laser

The Raman spectra from periodic structures was obtained under the usual backscateiing scheme.For excitation the radiation of Ar3-laser with power of 20-30 mW and wave length 488 nm was used.The beams were focused on a sample surface by telescopic objective in-spot with size less then periodgratings. The analysis of a spectral structure of nonelastic scattering of light was carried out using doublemonobromator DFS-24, with resolution not less than 2cm'.Experimental results.As a result of interference of two coherent beams on a samples surface the areas of various densityof laser radiation were formed. In places, where the radiation density reaches maximum, the modificationof PS layer occurs. The periodic structure with a period determined (