Patent ID: 8670665

Claim:
An optical apparatus, comprising: a plurality of converters to convert a pair of electrical signals into a pair of signal lights, wavelengths of the pair of signal lights being different from each other, the pair of electrical signals being modulated by a pair of pilot signals which comprise a normal phase and a reverse phase of the normal phase; a plurality of polarization controllers to control polarizing states of the pair of signal lights and outputting a plurality of polarization controlled lights respectively; an optical multiplexer to multiplex the plurality of polarization controlled lights into a multiplexed light; an optical splitter to branch the multiplexed light and outputting a branched light; a polarizer to extract light of a specified polarizing state from the branched light and outputting an extracted light; and a controller to detect an intensity of the extracted light and control the plurality of polarization controllers on the basis of the detected intensity, the detection of the controller being based on the pair of pilot signals.