aLIGO LHO Logbook

H1 SQZ

sheila.dwyer@LIGO.ORG - posted 11:12, Thursday 08 August 2019 - last comment - 14:54, Thursday 08 August 2019(51135)

squeezer laser current changed

D Sigg S Dwyer

Daniel found that the squeezer laser was multi mode after scanning the SHG from the control room. 

squeezer laser current now: 1.904A
when we got here: 1.870A

Things seem to be back to normal for now.

Comments related to this report

daniel.sigg@LIGO.ORG - 11:21, Thursday 08 August 2019 (51136)

Link

Laser power started droppping slowly about 2 days ago. It went multimode a little less than 3 hours ago.

Images attached to this comment

daniel.sigg@LIGO.ORG - 14:24, Thursday 08 August 2019 (51142)

Link

Didn't last. Another current increase to 1.950A. The output power of the squeezer laser has degraded by 10% over the last 2 days. This may be an indication that the pump diode is dying.

Images attached to this comment

sheila.dwyer@LIGO.ORG - 14:54, Thursday 08 August 2019 (51144)

Link

The first attachment shows about 5 months of trends of the squeezer laser powers both before and after the SHG, the right top panel shows power out of the laser in yellow and the power out of the SHG in green.  The earlier episodes of mode hopping show up as decrease green out of the SHG (because the IR power is in the wrong mode) but the IR power doesn't drop.  The last month and a half have been the most mode hop free we've had from the squeezer laser.

The last couple of days are the downturn at the end of the plot, showing that this incident is different in that the power out of the laser is dropping, quickly, as Daniel notes.

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