Binary relief phase-modulated gratings provide symmetrical diffraction of the incoming light beam. Asymmetrical gratings, e.g. asymmetrical triangular blazed gratings, are characteristic by an asymmetrical diffraction behavior, where one of the first diffraction orders is more important than the other one. Electron beam lithography is a suitable and flexible tool for patterning of such kind of gratings. High quality results can be readily obtained when the period of the grating is relatively large and the relief depth is relatively low, this is the case of gratings with a small blaze angle. As the blaze angle increases, the quality of result suffers from several patterning-related issues. One of the problems is a reflection of the incoming light beam from the back slope (anti–blaze facet) of the blaze grating. We propose a novel configuration, with a ribbed modulation of the back slope. This modulation is perpendicular to the direction of the grating grooves. This paper presents an analysis of the proposed blazed grating configuration. E-beam pattern generators were used to prepare a few samples of blaze gratings with a ribbed back slope. One part of the experiment was performed with a Gaussian-shaped beam and another one with the variable–shaped beam. Results of the experiment are presented. Finally, we discuss the optical performance of two blaze gratings with similar parameters, one of them is with the flat back slope and another one is with the ribbed back slope.Keywords: Nano patterning; blazed diffraction grating; Gaussian-type beam; variable–shaped beam; electron beam writer
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