US 11,677,209 B2
Blind pump laser detection
Zhiqian Zhu, Shanghai (CN); Ian Peter McClean, Brixham (GB); Yongjun Fu, Shanghai (CN); and Yongshi Gu, Shanghai (CN)
Assigned to II-VI DELAWARE, INC., Wilmington, DE (US)
Filed by II-VI DELAWARE, INC., Wilmington, DE (US)
Filed on Jun. 16, 2020, as Appl. No. 16/903,246.
Claims priority of application No. 201911283703.9 (CN), filed on Dec. 13, 2019.
Prior Publication US 2021/0184420 A1, Jun. 17, 2021
Int. Cl. H01S 3/13 (2006.01); H01S 3/067 (2006.01); H01S 3/094 (2006.01); G01R 19/165 (2006.01); H01S 3/16 (2006.01); H01S 3/10 (2006.01)
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
OG exemplary drawing
 
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.