Sub-half-micrometre gratings using e-beam lithography and reactive ion etching

A simple, manufacturable technique for the generation of sub-half-micrometre gratings in GaAs is demonstrated. The technique uses a single layer of polymethylmethacrylate photoresist, electron-beam lithography, and BCl3–He reactive ion etching to achieve high-quality second-order gratings. Good light attenuation properties are demonstrated for planar and ridge wave guides.