The calculation, fabrication and verification of diffraction grating based on laser beam splitters employing a white light scatterometry technique

In this work we present an application of polarized white light transmission and reflection measurements as well as simulation results for the analysis of diffractive optical elements, i.e. two port beam splitters for visible wavelength range lasers. A different pitch of 2, 4 mu m and a line height of 400-800 nm phase diffraction gratings were fabricated in fused quartz substrates employing contact lithography and plasma chemical etching. Line heights of the beam splitters targeted for 405-633 nm wavelength lasers were selected according to a straightforward analytical method. The resulting beam splitters were analyzed performing angular polarized white light reflection and transmission spectra measurements illuminating an 0.7 cm(2) area of the sample. Varying the surface profile in the PCGrate and GSolver simulation software and comparing the estimated transmission and reflection spectra with the experimental ones we have deduced the actual profiles of the structures. The assessed geometrical parameters of the profile, i.e. line height, groove and ridge widths correspond to the ones obtained when employing scanning electron and atomic force microscopy. The proposed modeling and validation method appeared to be an appropriate tool in the control of production of beam splitters possessing more than 60% diffraction efficiencies. (c) 2013 Elsevier Ltd. All rights reserved.