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Entry   2nd stage amplifier issue, posted by Ronic Chiche at Optical room about lasers and optics 
    Reply   2nd stage amplifier issue, posted by Ronic Chiche at Optical room about lasers and optics 
       Reply   2nd stage amplifier issue, posted by Ronic Chiche at Optical room about lasers and optics 
Message ID: 35     Entry time: Fri Dec 13 15:56:22 2019     In reply to: 34
 Author: Ronic Chiche 
 Status: Fixed 
 Type: issue 
 Category: lasers and optics 
 Location: Optical room 
 Title: 2nd stage amplifier issue 

2nd stage output power was going down. We checked the pump diode technical data sheet and the operating temperature is [25°C:35°C].
We increased the chiller temperature setpoint from 19°C to 23°C. 
Then the output power increased (93mW on 2nd stage photodiode).

Ronic Chiche wrote:

Last time, we switched ON directly the 2nd stage at 6A without increasing/decrinsing slowly the current.
today, we switched ON the chiller, switched ON the 1st stage, switch ON the power supply of the 2nd stage at 0A and then we increased slowly the current until 6A... and the problem disappeared.

ARonic Chiche wrote:

the 2nd stage amplifier needed several hours (4-5h) to reach its nominal power (we look at photodiode level on a scope), instead of the awaited 30 minutes.

could it come from the probable spectrum shifting of the OneFive laser ?
(the power coming from the CVBG, coupled to the fiber, is lower than expected).

 

 

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