| 摘要 |
PROBLEM TO BE SOLVED: To generate a sub signal, to evaluate a repeater and to exchange switches to transmit the sub signal at the time of a fault without using a dedicated light source by transmitting 1st phase conjugate light and 2nd optical length phase conjugate light that undergoes intensity light modulation by the sub signal to an optical transmission line in common. SOLUTION: Phase conjugate light of wavelengths λ1 and λ4 is selected and outputted from an optical filter 4. Further, a demultiplexer 5 divides an output of the filter 4 into optical signals of light wavelengths λ1 and λ4. The optical signal of the wavelength λ1 is phase conjugate light of main signal transmission and is sent to a multiplexer 6 as it is. An optical external modulator 7 modulates the optical signal of the wavelength λ4 divided by the demultiplexer 5 with a sub signal. An output of the modulator 7 is inputted together with the signal of the wavelength λ1 that is a phase conjugate signal for a main signal to the multiplexer 6, multiplexed and sent to an optical transmission line L. An output of the multiplexer 6 is propagated by the line L of a single mode optical fiber SMF and sent to a receiving end terminal station device II. |
