| 摘要 |
PURPOSE:To obtain a polyphase optical phase modulating device which has small loss to signal light by driving a two-phase PSK modulator with a many- valued amplitude signal and imposing polyphase optical phase modulation. CONSTITUTION:Data signals of two systems are converted into gray codes, etc., which are inputted as a signal for pi phase modulation and a signal for pi/2 phase modulation to a modulating signal input port 4 and a pi/2 modulating signal input port 5, and their amplitude adjuster 24 so that the amplitude ratio is 2:1. The output signal of the adder 16 becomes a quad code and the maximum amplitude is amplified by a driver amplifier 14 to 3/2 times the half-wave voltage Vpi of the two-phase PSK modulator 21 and the output modulating signal 15 is inputted to the modulating signal input port 12 of the PSK modulator 21 through a coaxial cable 13. Thus, the modulating signal is inputted and then four-phase PSK modulation is imposed upon light passed through an optical waveguide 1 corresponding to the respective levels of the quad code.
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