SYSTEM AND METHOD FOR POLARIZATION CONTROL BASED ON STRAIGHT WAVEGUIDE MODULATOR, AND QUANTUM KEY DISTRIBUTION SYSTEM

摘要

The present invention discloses a polarization control system and method, and a quantum key distribution system. According to the method of the present invention, a first electro-optic crystal and a second electro-optic crystal are used sequentially to perform phase modulation on signal light, wherein the signal light is propagated in the first electro-optic crystal as a horizontal polarized light component and a vertical polarized light component of ordinary light and extraordinary light, respectively, and the signal light is propagated in the second electro-optic crystal as extraordinary light and ordinary light. Modulated electric fields in the first electro-optic crystal and the second electro-optic crystal are both parallel to the polarization direction of the ordinary light or the extraordinary light in the corresponding electro-optic crystal, and have the same size; however, the directions of the modulated electric fields are opposite with respect to the direction of a straight line indicated by the polarization direction of the ordinary light or the extraordinary light in the corresponding electro-optic crystal. Thus, the polarization state of final signal light can be conveniently controlled by controlling a modulated electric field.