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ShalikaSingh - 19:15, Friday 26 January 2024 (3414)Get code to link to this report
Faraday Isolator and CrossPol setup for LC

After beam characterization, the following components were setup.

The faraday isolator we have is FI-1060-5SC-HP and has aperture of 5mm. QWP and HWP was placed before the FI to tune the input polarization to be linear. The azimuth and ellipticity were both (0.0±0.01)º . The faraday isolator alignment was done at power of around 15mW. The isolation was ~83 dB after tuning of the polarizers of the FI. Also, the transmission from FI was ~94%. The FI has aperture of 5mm hence it was placed within 200 mm from the laser shutter. The beam characteristics were used for optimal positioning.

After the FI, two lenses of f = -50 mm, and 75 mm were installed to have a collimated beam and were placed within 210 mm to 230 mm. The choice of lens was done using the Q parameter previously obtained in 3413 and 3410 in Jammt.

After the FI the beam is steered towards BSN11(R=10%).  The transmission line is intended to used for be used for pockel cells.

The reflected beam from above is incident on BST11(R=70%). The transmission of this will be used for LC setup. The reflection is incident on power meter to monitor laser beam fluctuation. See the new setup for better info. I had to remove BST11 and is not present in picture, as I accidentally touched it and had my fingerprint.

For the LC path, we use QWP and HWP to gain perfect linear polarization light. The azimuth and ellipticity were both 0.0° ±0.01°.

Finally, a polarizer was installed before the camera. The setup is now in cross polarization polarizer configuration and ready to characterize LC.

Comments related to this report
ShalikaSingh - 20:38, Friday 26 January 2024 (3415)

Also, in the cross polarizer setting, I saved some data of power. 

foldername= r'C:\Users\atama\OneDrive\LC-Experiment\Measurement Data\CrossPol'
filename= 'Thu, Jan 25, 2024 3-37-57 PM.txt'

ShalikaSingh - 18:31, Monday 29 January 2024 (3417)

I made a mistake in calculating the isolation ratio

mistake: -10*np.log(3.6e-6/15e-3) = 83.35 dB

correct: -10*np.log(270e-6/15e-3) = 40.17 dB

The isolation from faraday isolator is 40.17 dB