Patent ID: 9274354
Filing Date: 2016-03-01
CPC Classification: G02F

Claim Text:
1. A polarization control device, comprising: a first polarization converter for converting a polarization angle of an input optical signal in response to first control voltages; a second polarization converter for converting a polarization angle of the input optical signal in response to second control voltages; a third polarization converter for converting an optical signal received from the first polarization converter or the second polarization converter into a first output optical signal having a linear polarization state and outputting the first output optical signal; a polarization unit for controlling power of the first output optical signal; a photodetector for detecting power of the optical signal received from the polarization unit and outputting a feedback signal corresponding to the detected power; and a controller for controlling intensity of the first control voltages or the second control voltages in response to the feedback signal and resetting the first control voltages or the second control voltages when the first control voltages or the second control voltages reach a threshold value, wherein, when the first control voltages are reset, the first polarization converter stops its conversion operation and the second polarization converter starts its conversion operation, when the second control voltages are reset, the second polarization converter stops its conversion operation and the first polarization converter starts its conversion operation, the first control voltages comprise a first voltage applied to the first electrode of the first polarization converter, a second voltage applied to the second electrode of the first polarization converter, and a third voltage applied to the third electrode of the first polarization converter, the first voltage and the third voltage are varied in response to the feedback signal, and the second voltage is a ground voltage; and the second control voltages comprise a fourth voltage applied to the first electrode of the second polarization converter, a fifth voltage applied to the second electrode of the second polarization converter, and a sixth voltage applied to the third electrode of the second polarization converter, the fourth voltage and the sixth voltage are varied in response to the feedback signal, and the fifth voltage is a ground voltage.