Rectangular-profile diffraction grating from single-crystal silicon.

Diffraction gratings having well-shaped rectangular profiles were fabricated by chemical etching of single-crystal silicon oriented in the ?110? direction. The grooves were 2.62 microm deep, 5.4 microm wide, and were separated by 10.2 microm. The diffraction behavior was measured near normal incidence using several laser wave-lengths. The specularly reflected (zero-order) beam varied by a factor of at least 140 at different visible wavelengths, thereby demonstrating the excellent geometric form of the structures.