Fabrication of small period blazed reflection gratings by fast atom beam dry etching method

Abstract

This paper presents electromagnetic analysis of Si-based small period blazed reflection gratings for a period of 0.6 - 1.5μm in terms of rigorous coupled wave analysis (RCWA) and its fabrication by using dry etching method. Also, diffraction characteristics on the facet material are discussed on the basis of its efficiency. First, the optical and geometrical characteristics of blazed gratings are investigated and the first order diffraction efficiencies for TE and TM polarization are estimated under the phase-matching requirement for four kinds of gratings (period 0.6-1.5μm). Second, the optimized blazed gratings are successfully fabricated on a slanted silicon substrate by FAB etching method. From the results, the first-order TE and TM polarized diffraction efficiencies for four kinds of gratings are evaluated from optical testing and these results showed good agreement with these theoretical values, respectively. Also, it was found that diffraction efficiencies of gratings with the smaller period than the wavelength in dimension are obtained 0% for TE and TM polarization as expected. It is expected that this dry etching method for small size patterning in company with coating technology can be applicable to high performance optical devices.