Microgratings for high-efficiency guided-beam deflection fabricated by electron-beam direct-writing techniques

An electron-beam writing apparatus with a computer-processed scanning system has been developed to fabricate various types of microgratings in integrated optical circuits. As one of the most fundamental components, we have fabricated microgratings for high-efficiency guided-beam deflection in As(2)S(3) film waveguides. The design procedure was established for both uniform-period gratings and linearly chirped gratings.Uniform-period gratings 0.2 x 1 mm(2) exhibited excellent optical performance as designed, a diffraction efficiency eta approximately 100%. Chirped gratings exhibited wideband selectivity with high diffraction efficiency. Design and experimental results of microdeflection gratings are discussed in detail.