| 摘要 |
<P>PROBLEM TO BE SOLVED: To suppress effects of dispersion, PMD, and nonlinear phenomena by reducing the number of oscillators necessary for optical subcarrirer generation and a driving frequency to ≤1/2 of that of a conventional art and narrowing an occupied band in optical transmission. <P>SOLUTION: Conversion to such a modulator driving signal that subcarriers of light are generated with a frequency having fixed power as a center is performed, and continuous light is modulated to an optical subcarrier signal by using the modulator driving signal. When optical modulation is performed by an optical quadrature modulator, for example, transmission data are converted to two pieces of parallel data A(t) and B(t), and an I component signal resulting from modulating A(t)+B(t) by a clock signal having a frequency ω and a Q component signal resulting from modulating A(t)-B(t) by a signal resulting from shifting a phase of the clock signal by π/2 are generated, and the I component signal and the Q component signal are applied to respective electrodes of the optical quadrature modulator. <P>COPYRIGHT: (C)2008,JPO&INPIT |
