OPTICAL TRANSMISSION EQUIPMENT, OPTICAL TRANSMISSION SYSTEM, AND RAMAN AMPLIFIER CONTROL METHOD

1 . An optical transmission equipment comprising:

an optical transceiver circuit that transmits and receives signal light and supervisory light;

a forward Raman amplifier provided at a transmitter end of the optical transceiver circuit;

a backward Raman amplifier provided at a receiver end of the optical transceiver circuit; and

a processor that controls the forward Raman amplifier and the backward Raman amplifier,

wherein when a counterpart backward Raman amplifier or a counterpart forward Raman amplifier provided at an opposite side through a fiber-optic transmission line is started up, the processor turns off a power of the forward Raman amplifier or the backward Raman amplifier according to a supervisory signal received from the fiber-optic transmission line, and releases an off state of the forward Raman amplifier or the backward Raman amplifier after a predetermined period of time.

2 . The optical transmission equipment as claimed in claim 1 ,

wherein the predetermined period of time is longer than a time required for measuring optical pumping characteristics of the counterpart backward Raman amplifier or the counterpart forward Raman amplifier provided at an opposite end of the fiber-optic transmission line.

3 . The optical transmission equipment as claimed in claim 1 ,

wherein the processor shuts down the forward Raman amplifier and starts a timer upon receiving a forward Raman amplifier shutdown instruction from a second optical transmission equipment across the fiber-optic transmission line, and releases a shutdown state of the forward Raman amplifier upon elapse of time set in the timer.

4 . The optical transmission equipment as claimed in claim 1 ,

wherein the processor shuts down the backward Raman amplifier and starts a timer upon receiving a backward Raman amplifier shutdown instruction from a second optical transmission equipment across the fiber-optic transmission line, and records a noise power or a signal power due to forward Raman pumping of the second optical transmission equipment.

5 . The optical transmission equipment as claimed in claim 4 , wherein the processor releases a shutdown state of the backward Raman amplifier upon elapse of time set in the timer, and transfers the noise power or the signal power to the second optical transmission equipment.

6 . An optical transmission system comprising:

a first optical transmission equipment having a first forward Raman amplifier and a first backward Raman amplifier; and

a second optical transmission equipment connected to the first optical transmission equipment via a fiber-optic transmission line and having a second forward Raman amplifier and a second backward Raman amplifier,

wherein when bidirectional Raman pumping is started between the first optical transmission equipment and the second optical transmission equipment, one of the first optical transmission equipment and the second optical transmission equipment receives a supervisory signal via the fiber-optic transmission line from another one of the first optical transmission equipment and the second optical transmission equipment, turns off a Raman amplifier designated by the supervisory signal, and turns on the Raman amplifier after a predetermined period of time.

7 . The optical transmission system as claimed in claim 6 ,

wherein the predetermined period of time is longer than a time required for measuring optical pumping characteristics of a counterpart Raman amplifier located across the fiber-optic transmission line opposite to the Raman amplifier.

8 . The optical transmission system as claimed in claim 6 ,

wherein the first optical transmission equipment receives a shutdown instruction for the first forward Raman amplifier from the second optical transmission equipment when the optical pumping characteristics of the second backward Raman amplifier are measured, and shuts down the first forward Raman amplifier and starts a timer, and

wherein the first optical transmission equipment releases a shutdown state of the first forward Raman amplifier when the timer has expired.

9 . The optical transmission system as claimed in claim 6 ,

wherein the second optical transmission equipment receives a shutdown instruction for the second backward Raman amplifier from the first optical transmission equipment when the optical pumping characteristics of the first forward Raman amplifier are measured, and shuts down the second backward Raman amplifier, and

wherein the second optical transmission equipment starts a timer upon shutdown of the second backward Raman amplifier, and records a noise power or a signal power caused by the first forward Raman amplifier.

10 . The optical transmission system as claimed in claim 9 ,

wherein the second optical transmission equipment releases a shutdown state of the second backward Raman amplifier when the timer has expired, and transfers the noise power or the signal power to the first optical transmission equipment.

11 . A Raman amplifier control method comprising;

at an optical transmission equipment having a forward Raman amplifier and a backward Raman amplifier, turning off a power of the forward Raman amplifier or the backward Raman amplifier according to a supervisory signal received from a fiber-optic transmission line when the forward Raman amplifier or the backward Raman amplifier is started up, and

after a predetermined period of time, autonomously releasing a power-off state of the forward Raman amplifier or the backward Raman amplifier.

12 . The Raman amplifier control method as claimed in claim 11 , wherein the predetermined period of time is longer than a time required for measuring optical pumping characteristics of the counterpart backward Raman amplifier or the counterpart forward Raman amplifier provided at an opposite end of the fiber-optic transmission line.