POLARIZATION CONTROLLING CIRCUIT AND METHOD

摘要

PROBLEM TO BE SOLVED: To provide a polarization controlling circuit and method having high controlling speed and low controlling voltage.

SOLUTION: When an optical signal is inputted in a polarization beam splitter 32, the optical signal is divided into two optical signals having linearly polarized waves orthogonal to each other. Optical power levels of these two optical signals are respectively monitored by photo diodes 33 and 34 and optical intensity levels detected by the photo diodes 33 and 34 are inputted in a comparator 35. A compared result of the comparator 35 is inputted in a 2×2 optical switch 36 and the 2×2 optical switch 36 outputs the optical signal having the higher optical power level of the two optical signals into which divided by the polarization beam splitter 32 based on the compared result of the comparator 35.

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