40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  40m Log  Not logged in ELOG logo
Entry  Wed Jun 13 12:21:09 2018, gautam, Update, ALS, PDFR laser checkout 
    Reply  Wed Jun 13 22:07:31 2018, gautam, Update, ALS, BeatMouth PDFR measurement IMG_7056.JPGBeatMouthPDFR.pdfBeatMouth_PDFRdata.tgz
       Reply  Fri Jun 15 14:22:05 2018, gautam, Update, ALS, BeatMouth PDFR measurement BeatMouthPDFR.pdfBeatMouth_PDFRdata.tgz
Message ID: 13955     Entry time: Wed Jun 13 12:21:09 2018     Reply to this: 13957
Author: gautam 
Type: Update 
Category: ALS 
Subject: PDFR laser checkout 

I want to use the Fiber Coupled laser from the PDFR system to characterize the response of the fiber coupled PDs we use in the BeatMouth. The documentation is pretty good: for a first test, I did the following in this order:

  • Removed the input fiber to the 1x16 splitter located in the rack near the OMC chamber.
  • Connected aforementioned fiber to a collimator.
  • Aligned the output of the collimator onto a razor beam dump.
  • Turned on the laser controller - it came on with a TEC temperature of 22.5 C and I_diode 0 mA, and the "output shorted" LED was ON (red).
  • Turned up the diode current to 80 mA, since the "threshold current" is stated as 75 mA in the manual. In fact, I could see a beam using an IR card at 30 mA already.
  • At 80mA, I measured 3.5 mW of output power using the Ophir.

Seems like stuff is working as expected. I don't know what the correct setpoint for the TEC is, but once that is figured out, the 1x16 splitter should give me 250 uW from each output for 4mW input. This is well below any damage threshold of the Menlo PDs. Then the plan is to modulate the intensity of the diode laser using the Agilent, and measure the optoelectronic response of the PD in the usual way. I don't know if we have a Fiber coupled Reference Photodiode we can use in the way we use the NF1611 in the Jenne laser setup. If not, the main systematic measurement error will come from the power measurement using a Fiber Power Meter.

ELOG V3.1.3-