Combined blazed grating/Gires-Tournois resonator for liquid crystal beam switching

A new concept of liquid crystal (LC) beam switching structure is introduced and analyzed. The main advantages of this device are its ability to perform triple-state beam switching, using a single uniform electrode as well as its reduced LC thickness, leading to a potentially fast response. The device is also aimed at overcoming the problems associated with the use of LC index mismatch in a hybrid surface-relief blazed grating. The configuration is based on an embedded blazed diffractive grating, composed of two optical substrates with different refractive indexes and a uniform-thickness LC layer, enclosed in a Gires-Tournois resonator. It is shown that this structure, which also removes the difficulty of LC alignment in hybrid blazed LC-glass structures, allows a dynamic switching of a laser beam with a diffraction efficiency exceeding 67%.