| 摘要 |
PURPOSE:To efficiently enable diffraction demultiplexing operation by crossing the traveling direction of a light beam to be demultiplexed by demultiplexing in an electrooptic material and the traveling direction of progressive wave phase gratings, and providing at least three cycles of phase gratings in section crossing the phase gratings. CONSTITUTION:A couple of electrodes 3 and 4 which extend in one direction are formed on the electrooptic material body 2 which varies in refractive index with an applied electric field and when a high-frequency voltage is applied between those electrodes, the progressive wave phase gratings are formed in the electrooptic material body 2. When an incident light beam is made to travel crossing an electric wave forming this phase gratings, the number of the phase gratings present in the section of the light beam increases substantially and the diffraction efficiency increases. Therefore, many subordinate beams which are frequency-modulated can be separated spatially. Consequently, the electrooptic material element is applied to the demultiplexer device for generating the frequency-modulated subordinate beams, so that the subordinate beams which are modulated at a higher frequency than an acoustooptical element can be generated. |
