It is demonstrated theoretically and experimentally that the inversion symmetry of the diffraction pattern of a binary grating at normal incidence can be efficiently broken by the use of nonsymmetric profiles with wavelength-scale transverse features. Theoretically, binary gratings with two grooves (of unequal widths but with the same depth) within the period can deflect as much as similar to 80% of normally incident radiation into the minus first diffraction order when the deflection angle is 45 degrees. [References: 15]
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