PURPOSE: To monitor repetition by returning a response signal to the terminal station of a present circuit without changing the operating state of the optical fiber amplifier of the optical repeater at an optical signal repetition system.
CONSTITUTION: A repeater instruction is transmitted from a terminal station 2 while being superimposed to a main signal. At a repeater 1b, the residual light of excited light is reached through an optical transmission line 3 to a preceding step repeater 1a by exciting an erbium doped optical fiber 10b backward with an excitation light source 12b. Therefore, at the optical repeater 1b, the response signal is generated by a control circuit 14b and can be transmitted to the preceding step repeater 1a by modulating the amplitude of the excitation light source 12b.
JPH03252232A | 1991-11-11 | |||
JPH03270520A | 1991-12-02 | |||
JPH03252230A | 1991-11-11 |
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