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Entry  Wed Feb 24 00:27:14 2010, Dmass, Lab Infrastructure, Doubling, Doubling Crystal Damaged 
    Reply  Thu Feb 25 01:00:31 2010, Dmass, Lab Infrastructure, Doubling, Doubling Experiment Update! 
       Reply  Fri Feb 26 01:50:06 2010, Dmass, Lab Infrastructure, Doubling, Doubling Experiment Update! 
          Reply  Fri Feb 26 16:19:05 2010, Dmass, Lab Infrastructure, Doubling, Doubling Experiment Update! PD1AnaNoise.pdfPD2AnaNoise.pdfPD3AnaNoise.pdfPD4AnaNoise.pdf
Message ID: 623     Entry time: Fri Feb 26 16:19:05 2010     In reply to: 622
Author: Dmass 
Type: Lab Infrastructure 
Category: Doubling 
Subject: Doubling Experiment Update! 

Of course, one might ask why I rebuilt the Mach Zehnder readout...

Here are plots of the various PDs with one arm blocked and the HEPA on (I lated checked that the HEPA being off didn't really fix the coherence). Things to note:

  • The black trace is the frequency domain subtraction of the two signals from one wavelength. The subtraction agrees with the subtraction predicted by the coherence (not shown).
  • The PD noise is very much not limiting my measurement, however, the coherence was terrible.
  • I think this had something to do with the huge path length between my prism and my PDs, which could make jitter couple in very strongly.
  • The 532 noise limits were "bad", but is consistent with what you expect from the current noise of an AD829 coupling through a 50k transimpedance resistor (using LISO).

In conclusion, I think I was geometry limited before (using prisms), and I am rebuilding the readout with an SNR of 1000. This is more than 3, so its better

Op Amps:

  • I want to use AD743s for the I to V converter in my Si PDs, they have decent voltage noise with a 100k transimpedance resistor.
  • (I also looked at the AD829 and confirmed that it is fine with a 500 Ohm transimpedance resistor at DC).
  • Plots to come as I play with gnuplot
Attachment 1: PD1AnaNoise.pdf  65 kB  | Hide | Hide all
PD1AnaNoise.pdf
Attachment 2: PD2AnaNoise.pdf  65 kB  | Hide | Hide all
PD2AnaNoise.pdf
Attachment 3: PD3AnaNoise.pdf  64 kB  | Hide | Hide all
PD3AnaNoise.pdf
Attachment 4: PD4AnaNoise.pdf  65 kB  | Hide | Hide all
PD4AnaNoise.pdf
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