| 摘要 |
An optical communication system is described which comprises an optical source; an optical modulator, receiving a transmission signal having frequencies included within a signal band and adapted to emit a modulated optical signal of a predetermined optical bandwidth; an optical transmission line comprising an optical fibre portion; an optical receiver adapted to receive the optical signal in the presence of a predetermined SNR in the signal band, measured in a 5 MHz band. The telecommunication system further comprises, optically connected between the optical modulator and the optical transmission line, a depolarizer comprising two polarization-maintaining optical fibre portions, optically connected with each other in such a manner that the respective polarization axes form an angle of 45 DEG , in which the optical bandwidth, lengths and birefringence of the polarization-maintaining optical fibres are operatively selected so that the SNR at the receiver in the signal band does not differ more than 1 dB from the SNR at the receiver measured in a band of 5 MHz by substituting the optical fibre portion of the transmission line with a passive attenuator of same attenuation. <IMAGE> |
