Patent ID: 9264142
Filing Date: 2016-02-16
CPC Classification: H04B

Claim Text:
1. An RZ (return to zero) optical modulator, comprising: an RZ carver that outputs an optical pulse train of an RZ code; a polarization adjustment unit that improves a polarization extinction ratio of the optical pulse train outputted from the RZ carver and outputs the optical pulse train whose extinction ratio is improved; an optical modulation unit that modulates the optical pulse train outputted from the polarization adjustment unit and outputs the modulated optical pulse train, wherein the optical modulation unit polarization-multiplexes the modulated optical pulse train and outputs a polarization-multiplexed optical signal; a monitor unit that outputs a light intensity of each of polarizations of the modulated optical pulse train; and a control unit that controls a polarization angle of the optical pulse train to the optical modulator outputted from the polarization adjustment unit based on an output of the monitor unit.