reference sample measurement:

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Pump power = 0.029W with laser current I=0.77A

633nm probe

14:00 many scans

then adjust the pump alignment maximizing the signal

AC goes from 0.11V to 0.13 V

16:00 many scans

the imaging unit relative position is 13.4

DIDN'T CHECK THE MAXIMUM(for IU POSITION)

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1310nm probe laser current=200mA power 41.8mW without filter

after putting filter OD2 --> 

16:45 start scans to find the max

Refer to the plot legend with file names:

'Mon, Oct 16, 2017 4-45-02 PM.txt'

'Mon, Oct 16, 2017 5-00-39 PM.txt'

'Mon, Oct 16, 2017 5-02-15 PM.txt'

low signal to noise ratio

 

cannot go over AC=22mV , so increased the probe laser current from 200mA to 250mA

17:20 scan: 'Mon, Oct 16, 2017 5-20-07 PM.txt'

better signal to noise ratio but shape doesn't have side peaks... phase is strange

 

17:45 using the pinhole, reset the position of the pump

scan

 

17:52 scan:   'Mon, Oct 16, 2017 5-53-16 PM.txt'

the peaks have a different positions from before because the pump beam position was changed (at 17:45)

 

cannot see the central large peak because of heavy misalignment

 

adjust maximum of DC and scan again

17:58 scan: 'Mon, Oct 16, 2017 5-58-45 PM.txt';

still strange shape but different from before

 

set z=34mm and maximize the AC moving the pump

scan: 'Mon, Oct 16, 2017 6-08-56 PM.txt'

change the IU alignment and scan: 'Mon, Oct 16, 2017 7-27-00 PM.txt'

 

my opinion is that we have to adjust the alignment of the IU.

Maybe a different size of the beam on the PD or a different PD position