Reports until 15:25, Friday 07 June 2024
GQuEST General
Torrey Cullen - posted 15:25, Friday 07 June 2024 - last comment - 21:59, Wednesday 12 June 2024(11640)
Filter cavity suppression crude measurement

[Daniel, Sander, Torrey]

Attemped to measure the amount of power suppression the cavity is providing for the 1550 path. Plan was to use a camera, take a pic, fit a gaussian to the beam, then integrate to get total power. Do this for both beams without having to calibrate into units of power we could get a relative suppression via the ratio. THe problem is there is too much power when the modes align, as the camera saturates. And the 1550 ND filters we have are dirty. I attempted it with the power meter and got the following transmission values:

.550 mW When the two modes are maximally coresonant.

9 nW When the two modes are minimally coresonant. (blocking the 1550 beam reduces the reading down to the background level)

7 nW Background.

If we believe this very crude measurement this is a suppression factor of 2.75 * 10^5.

Comments related to this report
Daniel Grass - 15:32, Friday 07 June 2024 (11641)

If the transmitted beam were a TEM00 mode in both cases (which I doubt based on the camera), this would imply a finesse of 

\[ \mathcal{F} = \frac{\pi}{2} \sqrt{S} = 820\]

Where S is the supression factor, S>1.

Torrey Cullen - 21:59, Wednesday 12 June 2024 (11652)

The AOM frequency may not have been correctly maximizing the cavity transmission here.