| 摘要 |
An optical amplifier comprises an optical fibre, a pump laser for optically pumping the optical fibre to amplify an optical signal, a TEC 1 for cooling the pump laser on receipt of a cooling current, a temperature sensor 2 for monitoring the temperature of the amplifier housing; and a control circuit 3 for controlling the cooling current in dependence on a sensing output from the temperature sensor 2, so as to maintain the temperature of the pump laser at a temperature set point. The control circuit 3 is configured (i) to maintain the temperature of the pump laser at a first temperature set point within a predetermined temperature range of the amplifier, and (ii) to maintain the temperature of the pump laser at a second temperature set point, higher than the first temperature set point, when the sensing output from the temperature sensor 2 exceeds a threshold value. The feature that the temperature set point is raised to a higher level when the temperature of the pump laser goes above a preset level reduces the amount of self-heating of the pump laser, and thus prevents a thermal runaway situation.
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