CPC H01S 3/1305 (2013.01) [G01R 19/16571 (2013.01); H01S 3/0677 (2013.01); H01S 3/06716 (2013.01); H01S 3/094003 (2013.01); H01S 3/10023 (2013.01); H01S 3/1301 (2013.01); H01S 3/1608 (2013.01); H01S 2301/02 (2013.01)] | 23 Claims |
1. An erbium doped fiber amplifier (EDFA), comprising:
an input photodiode configured to generate a control signal based on an input signal;
a first stage coupled to the input photodiode, the first stage configured to generate an amplified signal based on the control signal from the input photodiode and the input signal;
a second stage coupled to the input photodiode and the first stage, the second stage configured to generate an output signal based on the amplified signal of the first stage, the control signal from the input photodiode, and a feedback signal, wherein a driver signal within the second stage is generated based on the feedback signal and the control signal from the input photodiode;
an output photodiode configured to generate the feedback signal based on the output signal; and
an alarm device coupled to the second stage, wherein the alarm device is configured to generate an alarm signal when the driver signal within the second stage exceeds a threshold value, wherein, when the first stage fails, the amplified signal within the first stage approaches zero, which causes the feedback signal from the output photodiode to approach zero and the driver signal within the second stage to increase and exceed the threshold value.
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