In the method according to the present invention, an optical fiber transmission
line for transmitting signal light is first provided. A Raman repeater 16 having
a pumping source for supplying pump light propagating in a direction opposite to
the direction of propagation of the signal light to the optical fiber transmission
line is provided in the middle of the optical fiber transmission line. A terminal
device having a similar pumping source is provided at one end of the optical fiber
transmission line. A control signal is transmitted to the Raman repeater 16
by the pump light from the terminal device. The Raman repeater is controlled
by the control signal transmitted. According to this method, the Raman repeater
is controlled by the pump light from the terminal device provided at the receiving
end, thereby eliminating a problem arising in the case of control by signal light
as in the prior art.
