DIFFRACTION GRATING WITH RECTANGULAR GROOVES EXCEEDING 80-PERCENT DIFFRACTION EFFICIENCY

A novel design for a surface relief grating with rectangular grooves i s presented. The first reflected diffraction order shows experimentall y 84% diffraction efficiency for a metallic grating. The required bina ry surface relief can be manufactured by using one single microlithogr aphic fabrication step similar to standard processes in microelectroni cs. Each period of the grating consists of a subwavelength ''minilatti ce'' with a variable duty cycle. A theoretical model of the structure is presented and compared to measurements at 10.6 mum wavelength. Appl ications ranging from deflectors, polarizing beam splitters, variable attenuators to general diffractive components such as kinoforms for la ser beam shaping are proposed.