Beam splitters based on double-layer rectangular phase gratings

Theoretical beam splitting characteristics of double-layer rectangular phas e gratings (DLRPGs) are reported. Computer simulation shows that these DLRP Gs not only can be used as common beam splitters with higher than 89% diffr action efficiencies and 95% energy distribution uniformities but also exhib it novel splitting properties; one DLRPG can generate a series of beam numb ers with 70% diffraction efficiencies by changing in real time the incident angles of a reading beam. This means that a single beam splitter can opera te as several common beam splitters.