| 摘要 |
PROBLEM TO BE SOLVED: To keep a high S/N by adding an optical amplifier to each channel between an optical demultiplexer and an optical multiplexer respectively, so as to compensate a luminous intensity loss caused in a route from the optical demultiplexer to the optical multiplexer. SOLUTION: N-sets of optical amplifiers 5-1-5-N are provided between N-sets of optical modulators 2-1-2-N and N-sets of optical delay devices 3-1-3-N are provided to compensate a signal loss. That is, for example, since outputs of 4-sets of optical modulators 2-1-2-4 are amplified by 4-sets of the optical amplifiers 5-1-5-4, a power level after a decreased optical modulator is much amplified by the 4-sets of the optical amplifiers 5-1-5-4 and given to the 4-sets of the optical delay devices 3-1-3-4. Since the loss in the 4-sets of the optical delay devices 3-1-3-4 is not so high, the power level after the 4-sets of the optical delay devices 3-1-3-4 is sufficiently higher to a degree, withstanding a loss in the optical multiplexer, thereby increasing the power level after the optical multiplexer. That is, deterioration in the S/N is avoided. |
