Measurement sample 50mm 5/6 ; effect of the strain on the birefringence

50L, 5/6

average = 15
air r = 3 ; sample r = 13
center x= 323.565; y= 154.375 ; z=60
azy=0
air : Wed, Jul 3, 2024 2-04-01 PM.txt
sample : Wed, Jul 3, 2024 2-06-34 PM.txt

azy =15
air : Wed, Jul 3, 2024 2-51-23 PM.txt
sample : Wed, Jul 3, 2024 2-53-52 PM.txt

azy =30
air : Wed, Jul 3, 2024 3-31-49 PM.txt
sample : Wed, Jul 3, 2024 3-34-19 PM.txt

azy=45
air : Thu, Jul 4, 2024 8-47-25 AM.txt
sample :Thu, Jul 4, 2024 8-58-18 AM.txt

azy =60
air= Thu, Jul 4, 2024 9-38-32 AM.txt
sample=Thu, Jul 4, 2024 9-41-45 AM.txt

azy=75 air= Thu, Jul 4, 2024 10-25-24 AM.txt
sample=Thu, Jul 4, 2024 10-27-51 AM.txt

azy=90
air= Thu, Jul 4, 2024 11-41-35 AM.txt
sample= Thu, Jul 4, 2024 11-44-40 AM.txt

After this measurement we saw that the birefringence of this sample seems follow a very singular pattern. We suppose that this pattern can be induce by the strain of the screws use to fix the sample. So we decide to remove this screw and mad the same measurement with the same sample but without his two screw. The result is on the following measurement.

50L, 5/6 WITHOUT SCREWS STRAIN
average = 15
air r = 3 ; sample r = 13
center x= 323.565; y= 154.375 ; z=60
azy = 90
air: Thu, Jul 4, 2024 1-57-18 PM.txt
sample:Thu, Jul 4, 2024 2-00-03 PM.txt

azy=0 air = Thu, Jul 4, 2024 4-39-39 PM.txt
sample = Thu, Jul 4, 2024 4-42-12 PM.txt

azy=15 air=Thu, Jul 4, 2024 5-37-47 PM.txt
sample=Thu, Jul 4, 2024 5-40-16 PM

azy=30 air= Thu, Jul 4, 2024 6-39-02 PM.txt
sample:Thu, Jul 4, 2024 6-41-54 PM.txt

azy=45 air = Fri, Jul 5, 2024 7-44-42 AM.txt
sample = Fri, Jul 5, 2024 7-48-36 AM.txt

azy=60
air : Fri, Jul 5, 2024 8-25-22 AM.txt
sample :Fri, Jul 5, 2024 8-30-02 AM.txt

azy = 75
air : Fri, Jul 5, 2024 9-07-23 AM.txt
sample : Fri, Jul 5, 2024 9-07-23 AM.txt

Measurement sample, 50mm, 6/6

50L, 6/6
average = 15
air r = 3 ; sample r = 13
center x= 323.565; y= 154.375 ; z=60

0 deg without sample : Wed, Jul 3, 2024 7-05-19 AM
0 deg sample : Tue, Jul 2, 2024 5-13-54 PM

15 deg without sample : Wed, Jul 3, 2024 7-05-19 AM
15 deg sample : Wed, Jul 3, 2024 7-08-21 AM

30 deg without sample : Wed, Jul 3, 2024 7-46-08 AM
30 deg sample : Wed, Jul 3, 2024 7-48-54 AM

45 deg without sample : Wed, Jul 3, 2024 8-45-36 AM
45 deg sample : Wed, Jul 3, 2024 8-48-33 AM.txt

60 deg without sample : Wed, Jul 3, 2024 9-48-17 AM.txt
60 deg with sample :Wed, Jul 3, 2024 9-51-40 AM.txt

75 deg without sample : Wed, Jul 3, 2024 10-38-48 AM.txt
75 deg with sample : Wed, Jul 3, 2024 10-43-11 AM.txt

90 deg without sample : Wed, Jul 3, 2024 11-23-26 AM.txt
90 deg with sample : Wed, Jul 3, 2024 11-26-16 AM.txt

NB: data refound after the crash of logbook normally there is no probleme but if something seems wrong try to replace "0 deg sample : Tue, Jul 2, 2024 5-13-54 PM" by "0 deg sample : Tue, Jul 2, 2024 6-13-32 PM"

Test post

test

AlgasAs measurement at different angle of incidence

We measure by rotating the stage such that the reflected beam doesn't go through the BS. LC voltage scan is done from 0-3.5V with 0.1V step.

Normal incidence is at 172deg

Measurement @ 180 deg

C:\Users\atama\Dropbox\LC-Experiment\Measurement Data\Coating measurement\AlGaAs\20240701\180 deg\Tue, Jul 2, 2024 11-44-16 AM.txt

Measurement @ 190 deg

C:\Users\atama\Dropbox\LC-Experiment\Measurement Data\Coating measurement\AlGaAs\20240701\190 deg\Tue, Jul 2, 2024 3-39-54 PM.txt

Comment to ILM sample measurement (Click here to view original report: 3627)

Of course "with QWP" need to e replace by "with ILM sample"

Measure PCI sample 3 cm

We find the center of the sample at : X = 323.565 ; Y = 154.375 2 different measure with different input polarization : -"Mon Jun 10 2024 4-21-27 PM" : ele =0° ; azy = 89.85° -"Mon Jun 10 2024 5-36-33 PM.txt" : ele = 0° ; azy = 45° (step = 1mm ; map radius = 15mm)

OPO characterization in ATC - mode matching

Logan, Michael

We proceeded with trying to get the mode matching to the OPO. We have, as last time, a mode matching telescope consisting of f = 40mm and f = 75mm lenses which are mounted on millimeter rails. We saw that the height of the center of these lenses was 75mm and 77 mm. 

When we tried to do the mode matching previously we set the beam profiler at the nominal OPO waist position and then iteratively adjusted the lenses around their design positions in the same manner as the steering mirror beam walking alignment method. However, the beam profile was quite asymmetric at times. Somehow, last time we did this OPO test, we managed to get a quite good beam profile coming out of this mode matching telescope design (25.5 vs 26 um), despite the beam coming from the preset beam path (Lightwave Laser + lenses) being quite astigmatic (135 vs 160 um). However, in that case we had one steering mirror between the lenses at 45 degree incidence. We saw that the beam, which we had previously set to travel "approximately" along a set of screw holes at about 73mm height, was entering the first lens low and to the right, causing a large deflection to hit the second lens up and to the left. This might cause some difference in horizontal versus vertical focusing and also deflects the beam going into the beam profiler, making adjustment a bit annoying.

We decided to more precisely center the beam going to the mode matching telescope. Before, we set up this beam path by diverting the s-pol beam going to the Korean Faraday isolator. We replaced that mirror with a BSW11 50:50 beamsplitter then set up two steering mirrors at 45 degree incidence to more accurately set the beam path along a set of screw holes, this time at 75mm height. The beam was aligned iteratively along the path using the two steering mirrors and close/far targets. We also took a proper spacer to make the second lens at 75mm height. So now we have an adjustable beam going to our OPO MMT, as well as incidenct s-pol light on the Korean FI.

We took a steering mirror from the Taiwan SHG p-pol path. Since I will change the input coupler to one with a 1.53 mm diameter input beam (vs 4.5 mm clear aperture to meet the CA = 2.7D -> 1 ppm diffraction requirement), we are going to mess up this path either way. We were running out of mirrors so I took two Optosigma TVFM-25C05-1064 steering mirrors from the KFC box.

We also labelled some unlabelled optics on the table.

cc pll investigation

[Logan, Marc]

we started by replacing the PD battery by a spare one.

Then, by tuning the mode-matching of each fiber.

after some tweaking we have CC input 0.49mW and transmission 0.144mW and ML input 4.06mW and transmission 0.69 mW.

The ML transmission was highly fluctuating (maybe du to ceiling light?).

We could also recover the lock but as seen from the muxout 'digital lock detect'it is not stable at all...

p-pol pll recovery

[Logan, Marc]

We started with some issues to see the beatnote signal that was fluctuating and disappearing randomly. Some monitoring cables were cutting the main laser beam and this issue was resolved after moving them.

We recovered about 20% mode-matching for each beam.

We  could not change the DDS3 DAC1 frequency. What is surprising is that it can change when reloading a new config but not when just loading new frequency in an existing frequency.

We moved p-pol pll lo to DAC0 that is working properly.

To achive the lock, we had to change the phase detector polarity to negative as saved in the latest config file

Mounting AlGaAs on rotating stage

[Shalika, Marc, Hugo]

We have mounted the mirror on rotational stage to study the birefringence dependence on angle of incidence. The angle of rotator at normal incidence is 172 deg. The camera is mounted as well on this rotator stage, such that it can be placed radially infront of the coating. 

ILM sample measurement

New measurement : average = 15

Input polarisation 0 0 :
-without sample :Wed, Jun 26, 2024 8-28-22 AM.txt
-with QWP : Wed, Jun 26, 2024 8-31-55 AM.txt

Input polarisation 15 0 :
-without sample : Wed, Jun 26, 2024 9-09-25 AM.txt
-with QWP :Wed, Jun 26, 2024 9-19-36 AM.txt

Input polarisation 30 0 :
-without sample : Wed, Jun 26, 2024 10-15-42 AM.txt
-with QWP : Wed, Jun 26, 2024 10-23-04 AM.txt

Input polarisation 45 0 :
-without sample : Thu, Jun 27, 2024 9-55-00 AM.txt
-with QWP : Thu, Jun 27, 2024 12-20-38 PM.txt

Input polarisation 60 0 :
-without sample : Fri, Jun 28, 2024 9-33-51 AM.txt
-with QWP : Fri, Jun 28, 2024 9-38-24 AM.txt


Input polarisation 75 0 :
-without sample : Fri, Jun 28, 2024 10-16-40 AM.txt
-with QWP : Fri, Jun 28, 2024 10-19-00 AM.txt


Input polarisation 90 0 :
-without sample : Fri, Jun 28, 2024 11-10-10 AM.txt
-with QWP : Fri, Jun 28, 2024 11-13-12 AM.txt

OPO characterization in ATC- mode matching

Logan, Michael

We planned out a simple setup to mode match into the OPO (beam size 25.5 um before placement). We place f = 40 at z = 65 in and f = 75 at z = 71.6 in (screw holes relative to laser head). The beam size is then ~ 25um at z = 79, a slightly more comfortable spacing than last time the OPO was tested (maybe 5 cm extra). We have enough space to put both steering mirrors after the lenses and then put a 50/50 BS between the lenses to send to reflection PD (PDA05CF2 RFPD was used last time).

We checked using the mode matching telescope that the beam waists are approximately the correct places and the waist after f = 40 is about the right size (~40 um). Then we tried to optimize the mode matching at z = 79 but couldn't get below ~ 40 um radius.

We inserted Newport 4003 Resonant IR EOM somewhere down the line (aligned with 94% transmission). Since it is coming out of the reflection of a PBS (s-pol) I didn't add a HWP. Perhaps it added a bit more optical path length than I expected, I didn't check carefully in the clean room. From online search afterwards, the crystal is 4 cm long and made of Mg:LiNbO3 with a 25 C 1064 nm refractive index of 2.15. So it adds an extra ~ 4.5 cm (1.8in) of optical path and the initial positioning was a bit too far forward.

I'm not entirely sure if we have to lock, or if we even can lock before the Taiwan people arrive, but we might as well leave the EOM there anyway and see if we can lock by July 16. At the very least we should try to visualize good mode matching of the order used in the current OPO ( >  91% BAB to OPO). It is probably not worth the effort to test the loss using the AOM deflection method, since last time it was inconclusive due to the very fast ringdown. The only meaningful test of the new OPO loss will be inserting it into the squeezer.

Measurement PCI to find the optimal average

average = 1 : Tue, Jun 25, 2024 5-38-50 PM.txt
average = 10 : Tue, Jun 25, 2024 5-43-40 PM.txt
average = 20 : Tue, Jun 25, 2024 5-45-29 PM.txt
average = 50 : Tue, Jun 25, 2024 5-48-34 PM.txt
average = 100 : \Tue, Jun 25, 2024 5-54-16 PM.txt

QWP map

New measurement : average = 100

Input polarisation 0 0 :
-without sample : Mon, Jun 24, 2024 10-31-17 AM.txt
-with QWP : Mon, Jun 24, 2024 12-34-46 PM.txt

Input polarisation 15 0 :
-without sample : Mon, Jun 24, 2024 2-05-53 PM.txt
-with QWP : Mon, Jun 24, 2024 2-16-39 PM.txt

Input polarisation 30 0 :
-without sample : Mon, Jun 24, 2024 3-47-22 PM.txt
-with QWP : Mon, Jun 24, 2024 4-00-22 PM.txt

Input polarisation 45 0 :
-without sample : Mon, Jun 24, 2024 5-31-44 PM.txt
-with QWP : Mon, Jun 24, 2024 5-42-23 PM.txt

Input polarisation 60 0 :
-without sample : Tue, Jun 25, 2024 6-00-10 AM.txt
-with QWP : Tue, Jun 25, 2024 6-11-34 AM.txt


Input polarisation 75 0 :
-without sample : Tue, Jun 25, 2024 8-03-38 AM.txt
-with QWP : Tue, Jun 25, 2024 8-14-25 AM.txt


Input polarisation 90 0 :
-without sample : Tue, Jun 25, 2024 9-45-12 AM.txt
-with QWP : Tue, Jun 25, 2024 10-11-38 AM.txt

Comment to added HWP in front of AlGaAs coating (Click here to view original report: 3621)

Restarted measurement without wait time and same parameters otherwise

by mistake the first few points were saved in the previous file..

I stopped the vi and restarted maesurement C:\Users\atama\Dropbox\LC-Experiment\Measurement Data\Coating measurement\AlGaAs\with hwp\Mon, Jun 24, 2024 2-27-30 PM.txt

Comment to added HWP in front of AlGaAs coating (Click here to view original report: 3621)

There is no requirement to switch on wait time for any measurement. There is already an intrinsic wait time present in the labview logic. The external wait time is only to be switched on if you are doing stability measurement of the setup(for >~a day) and don't want to take measurement with high frequency. Unless there is a promising reason there is no use of switching on the external wait time for birefringence measurement of samples.

added HWP in front of AlGaAs coating

To confirm our AlGasAs birefringence measurement, we want to add a birefringent component between the BS and the coating.

I placed the HWP that was measured before (same roll angle as before).

Measurement from 0 to 3.5V with 0.1V step, LC temp is 30degC, 100 average and 1s wait time.

File is in : C:\Users\atama\Dropbox\LC-Experiment\Measurement Data\Coating measurement\AlGaAs\with hwp\Mon, Jun 24, 2024 10-47-05 AM.txt

PCI set-up

I reinstalled the QWP and the HWP in order to get a circular polarization after the last mirror. And I add a polarizer on a motorized mount, just before the translation stage. Like this, we can get any linear polarization with enough power, without going into the clean room.

I put as sample a QWP, everything seems ready to start a measurement.

IMPORTANT : LIMIT VALUE ON Z AXIS == 23mm. (avoid to hit the polarizer)

AlGasAs coating measurement

[Shalika, Marc]

Measuring Jones Matrrix of AlGaAs coating

The sample is same as mentioned by Manuel in 746. We used the mounting technique as mentioned by Manuel in 746. But, we put in a mount where we can tune the alignment as well, i.e in  a 2inch mirror mount. We first practiced putting a sample with no polish to see if the mount is fine. After being fully assured that the mount was indeed fine(like the screw will not touch the wafer or the wafer will not fall off, etc.), we then put the 0.5mm thick sampple. (pic1, pic2)

We setup a small clean room (taken from PCI). The AlGaAs was kept inside it. (pic3, pic4)

saving measurement from LC voltage scan in   in:

C:\Users\atama\Dropbox\LC-Experiment\Measurement Data\Coating measurement\AlGaAs\20240621\Fri, Jun 21, 2024 3-12-57 PM.txt

Comment to Re-characterizing the BS and measuring mirror (Click here to view original report: 3611)

I rotated the sample. Although its on non rotatble mount, I took a picture of the back surface for a reference of Sample 2 BB1EO3, before and after rotation.

C:\Users\atama\Dropbox\LC-Experiment\Measurement Data\Coating measurement\BB1-EO3 Sample2\20240619\Wed, Jun 19, 2024 6-42-43 PM.txt