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Entry  Thu Apr 14 17:30:18 2016, ericq, Update, General, PLL measurement ongoing 
    Reply  Fri Apr 15 03:02:44 2016, ericq, Update, General, New AUX laser measurements aux_innolight_freqPSD.pdfaux_innolight_AMPM.pdfaux_innolight_data.zip
       Reply  Fri Apr 15 18:35:57 2016, gautam, Update, General, New AUX laser measurements PSL_AUX_TEMP_SCAN.pdfPSL_AUX_TEMP_SCAN.mat
          Reply  Fri Apr 15 23:11:49 2016, gautam, Update, General, Innolight 1W moved to SP table 
             Reply  Mon Apr 18 00:29:00 2016, gautam, Update, General, Beam profiling + injection current scan 6x
Message ID: 12078     Entry time: Fri Apr 15 18:35:57 2016     In reply to: 12077     Reply to this: 12080
Author: gautam 
Type: Update 
Category: General 
Subject: New AUX laser measurements 

I've performed the temperature sweep of PSL vs Innolight 1W AUX laser.

  • I followed the procedure in this elog - started by turning of FSS and FSS Slow servos, closed the PSL shutter, noted down the value of PSL temperature
  • As noted in elog 3759, there are multiple temperatures at which a beat can be found. I recorded all that I could find. The IR beat frequency was < 20MHz at the temperatures recorded (and had an amplitude of a few dBm, but I used a 20dB coupler to look at the signal on the HP spectrum analyzer
  • The PMC unlocked each time I changed the PSL temperature, but the PMC autolocker worked for me every time
  • We should use curve 3 in attachment 1, it is the most reliable set of temperatures at which a beat can be found
  • PSL diode current was 2.100A, AUX laser diode current was 2.001A
  • Attachment 2 is the data

It remains to measure the output power vs diode current, and the beam profile. I will do the latter on the SP table where there is a little more space. Because we have 1W from this NPRO, the knife-edge method requires a power meter that has a large dynamic range and is sensitive enough to profile the beam accurately. After consulting the datasheets of the power meters we have available (Scientech, Ophir and Coherent) together with Koji, I have concluded that the Coherent calorimeter will be suitable. Its datasheet claims it can accurately measure incident powers of up to 100uW, although I think the threshold is more like 5-10mW, but this should still be plenty to get sufficient resolution for a Gaussian intensity profile with peak intensity of 1W. We also checked that the maximum likely power density we are likely to have during the waist measurement process (1W in a beam of diameter 160um) is within the 6kW/cm^2 quoted on the datasheet.

Attachment 1: PSL_AUX_TEMP_SCAN.pdf  59 kB  Uploaded Fri Apr 15 20:08:19 2016  | Hide | Hide all
Attachment 2: PSL_AUX_TEMP_SCAN.mat  1 kB  Uploaded Fri Apr 15 20:08:29 2016
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