Diffraction properties of double-layer rectangular phase gratings

We theoretically present diffraction properties of double-layer rectangular phase gratings (DLRPGs). Computer simulations show that these DLRPGs can r ealize several functions such as optical filtering, optical switching, opti cal amplitude modulating, beam splitting with variable output beam numbers and wavelength division multiplexing, and so on. As a test of the above dif fraction properties, we fabricate a set of DLRPGs in a double-layer light-s ensitive material by the contact printing method. Based on the DLRPGs of th e material, a single beam splitter with experimental results of splitting o f an incident beam into 2, 3 or 5 output beams and of higher than 64% total diffraction efficiency are realized when the incident angle of the readout beam is tuned during the reading process.