发明名称 |
QUADRATURE PHASE SHIFT KEYING (QPSK) MODULATOR |
摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a QPSK modulator that maintains a phase difference between the I phase and the Q phase to π/2. <P>SOLUTION: The QPSK modulator includes: a means for splitting incident light into two beams; a first phase modulating means for modulating the phase of one of the branched beams; a second phase modulating means for modulating the phase of the other branched beam; a phase shifting means disposed in a preceding stage or a succeeding stage of the first or second phase modulating means; a means for coupling the beams that have respectively passed through the first phase modulating means and the second modulating means, and outputting the coupled beams as an optical signal; a means for converting a part of the outputted optical signal into an electric signal; a means for detecting a peak value of the amplitude of the optical signal from the electric signal and outputting a peak detection signal; a means for generating a dither signal; a phase comparing means for comparing phases of the peak detection signal and of the dither signal and generating a deviation signal in accordance with the deviation from the phase shift amount π/2 in the phase shifting means; and a feedback control means for superposing the dither signal on the deviation signal and feedback-controlling the phase shifting means to adjust the phase shift amount to π/2. <P>COPYRIGHT: (C)2011,JPO&INPIT |
申请公布号 |
JP2011069924(A) |
申请公布日期 |
2011.04.07 |
申请号 |
JP20090219679 |
申请日期 |
2009.09.24 |
申请人 |
NIPPON TELEGR & TELEPH CORP |
发明人 |
HATTORI KUNINORI;FUKUYAMA HIROYUKI |
分类号 |
G02F1/01;G02F1/015;G02F1/03;G02F1/035;H04B10/07;H04B10/40;H04B10/50;H04B10/516;H04B10/548;H04B10/60;H04B10/61 |
主分类号 |
G02F1/01 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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