Optical Circular-Polarization Modulator Based On Liquid Crystal

with the development of the laser technology, the application domain of the polarized light expands. In optical communication systems, the optical circular polarization modulator can be used as a high speed coding modulator, in which information is coded by the selection of either left-hand-circular or right-hand-circular lights. The optical circular polarization modulator can also be employed as a light source for detecting and measuring chirality, and can find uses in remote sensing, scanned object detection in fog, and imaging polarimetry.As a widely used material, liquid crystal has a large electric-optic effect. The Electrically Controlled Birefringence effect of liquid crystal can be used to change the polarization state conveniently so that liquid crystal can be used to design the optical circular polarization modulator. The liquid crystal has the advantage of low driving voltage less than 10v.In this paper an optical circular polarization modulator based on liquid crystal is presented. On the basis of Electrically Controlled Birefringence of liquid crystal material, a control circuit is designed, which can ensure to output the stable circular-polarization states. Detailed illumination of the device's structure , circuit and software design are presented. This kind of optical circular polarization modulator has the advantage of low drive voltage less than lOv, fast response speed and small volume. The test results demonstrate the circular polarization degree of output light of this optical circular polarization modulator is above 99.9%.