Blazed binary subwavelength gratings with efficiencies larger than those of conventional échelette gratings

Philippe Lalanne (1) , Simion Astilean (2) , Pierre Chavel (2) , Edmond Cambril (3) , Huguette Launois (3)

1 Laboratoire Charles Fabry de l'Institut d'Optique / Naphel
2 Laboratoire Charles Fabry de l'Institut d'Optique / Scop
3 L2M - Laboratoire de Microstructures et de Microélectronique

We introduce a new structural cutoff beyond which subwavelength gratings cease to behave as homogeneous media and discuss its effects on the proper selection of the sampling periods of subwavelength diffractive elements. According to this analysis, a 3λ-period blazed binary grating composed of square pillars is designed for He-Ne operation and is fabricated by etching of a TiO>₂ layer deposited upon a glass substrate. Its first-order measured diffraction efficiency is 12% larger than the theoretical efficiency of an ideal blazed échelette grating in glass with the same period.

Domaines: Optique [physics.optics]

Philippe Lalanne, Simion Astilean, Pierre Chavel, Edmond Cambril, Huguette Launois. Blazed binary subwavelength gratings with efficiencies larger than those of conventional échelette gratings. Optics Letters, 1998, 23 (14), pp.1081-1083. ⟨10.1364/OL.23.001081⟩. ⟨hal-00877238⟩