Fabrication and analysis of transmission gratings produced by the indirect laser etching technique

Abstract

The diffraction efficiency of gratings etched into fused silica was measured and modelled. 950, 2120 and 3710 nm period gratings were fabricated with the use of two-beam interferometric laser-induced backside wet etching (TWIN-LIBWE). The spatial distribution of the modulation depth (MD), determined from AFM measurements, followed the spatial intensity distribution of the laser beam throughout the grooved areas. The diffraction efficiency of the fabricated gratings was measured to all allowed diffraction orders at several wavelengths (266, 532 and 654.5 nm). Within the frame of Gsolver code, a model was developed that takes into account the spatial distribution of MD. The computed diffraction efficiencies showed good agreement with the results of measurements.