Diffraction grating is one of the very important means to produce the diffraction and interference phenomena which demonstrate the wave nature of the light. Electrically tunable diffraction grating (ETDG) has been widely used for the laser beam steering, intensity modulators, display devices, optical interconnections, and so on. In order to improve the performances of ETDG, the newly developed transparent PMNT (PbMg1/3Nb2/3-xPbTiO3) electro-optic ceramic is one of the very ideal candidates. This ceramic belongs to the class of materials possessing relaxor properties, which easily produces birefringence and exhibits the electro-optic effect.
Researchers at Research Center of Space Laser Information Technology——Shanghai Institute of Optics and Fines Mechanics (SIOM/China) have proposed and demonstrated a novel reflection-type electrically tunable high-efficiency phase diffraction grating using the transparent lead magnesium niobate-lead titanite (PMNT) electro-optic ceramic, for the first time.[Optics Letters 36 (13), 2453, 2011]
With the photomask technique，they fabricated the grating with the Ti/Pt/Au interdigital electrodes. With the variation of the equivalent phase face induced by the quadratic electro-optic effect of the PMNT ceramic, the diffraction patterns of the light beam will be changed in which the diffraction efficiency may be controlled by an applied DC voltage. When the applied voltages are 41, 80, and 139 V, the zero-order, first-order, or second-order diffraction lights will disappear in turn with about 100% diffraction efficiency.The proposed grating can be used as an electrically controlled switch in the laser beam modulation and scanning, especially for the application of the high-power laser systems.
