Figure 4From: Multilayer porous silicon diffraction gratings operating in the infraredA cross-sectional SEM image (beam voltage of 0.5 kV) of PS diffraction gratings. Gratings were fabricated with a pitch of 4 μm; (a) single-layer grating of height h1 = 500 nm and (b) double-layer grating of heights h1 = 890 nm and h2 = 270 nm.Back to article page