| 摘要 |
PURPOSE:To improve a data speed by dividing the band characteristic of a band pass filter into plural number in matching with plural passing waves to increase the degree of freedom of selection of a carrier signal and spreading the pass band without deteriorating the S/N. CONSTITUTION:The titled circuit consists of a branching device 21, band pass filters 22, 23 and a synthesizer 24. After the optical signal modulated by carrier signals f0, f1 is divided into two by the branching device 21, the signal is inputted respectively into plural, e.g., two split band pass filters 22, 23. The characteristic of the band pass filter 22 has a narrow pass band W0 including the frequency f0 and the characteristic of the band pass filter 23 has a narrow pass band W1 including a frequency f1. Only the carrier signal f0 is outputted to the output of the band pass filter 22 and only the carrier signal f1 is outputted to the output of the band pass filter 23. The outputs of the two band pass filters 22, 23 are synthesized by the synthesizer 24 and outputted. That is, the band characteristic has the two narrow pass bands W0, W1. |
