Message ID: 13841
Entry time: Mon May 14 18:58:32 2018
In reply to: 13835
Reply to this: 14225

Author:

Kevin

Type:

Update

Category:

PonderSqueeze

Subject:

Squeezing with no SRM

Quote:

Note that for Signal Recycling, which is what Kevin tells us we need to do, there is a DARM pole at ~150 Hz.

To be quantitative, since we are looking at smaller squeezing levels and considering the possibility of using 5 W input power, it is possible to see a small amount of squeezing below vacuum with no SRM.

Attachment 1 shows the amount of squeezing below vacuum obtainable as a function of homodyne angle with no SRM and 5 W incident on the back of PRM. The optimum homodyne angle at 210 Hz is 89.2 deg which gives -0.38 dBvac of squeezing. Figure 2 is the displacement noise at this optimal homodyne angle and attachment 3 is the same noise budget shown as the ratio of the various noise sources to the unsqueezed vacuum.

The other parameters used for these calculations are:

4.5 kΩ series resistance for the ETM coils; 15 kΩ for the ITM coils

100 ppm transmissivity on the folding mirrors giving a PRC gain of 40

PD quantum efficiency of 0.88

So maybe it's worth considering going for less squeezing with no SRM if that makes it technically more feasible.