Application of Plasma Chemical Etching in Control of Optical Properties of Multilayered Dielectric Gratings

Abstract

In the present research we have fabricated 2 μm period diffraction gratings in multilayered dielectric (MLD) mirror with controlled diffraction efficiencies for the 532 nm wavelength of 80 % in I0 and 10 % in I±1 diffraction orders by plasmachemical etching (PCE) in CF4 / O2 gas mixture plasma. Etching rate after different durations of processing was found measuring diffraction efficiency and employing atomic force microscope. Diffraction efficiency was measured with two lasers of different power and wavelength: HeNe – 632.8 nm, 30 mW, diode pumped solid state – 532 nm, 1 mW. Transmission of the multilayered dielectric structures before and after PCE processing without the mask was estimated employing a spectrometer. MLD grating fabrication conditions of controlled optical properties were defined for two different feedstock gas ratios (15 % and 20 % of O2).