Polarization control in Fiber Optics
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- Опубліковано 30 лис 2024
- Link to my free E-book on the Nonlinear Schrodinger Equation:
github.com/Ole...
Explanations of polarization:
www.rp-photoni...
www.fiberoptic...
www.fiberoptic...
www.fiberoptic...
Thanks for the videos. Very well explained. It’s hard to find videos with theory explained in a practical way.
I have a SMF DFB laser but would like polarized light for SHG. As you explained, any movement of the SMF will cause changes in the polarization. Do you think if I glue down the SMF before the polarizer it would keep its polarization? Any other ideas are welcome. Thanks again!
You're welcome, I am glad that you found it useful!
As you can see at 6:00 onwards, the values measured by the power meters remains constant unless something the fiber is actively disturbed. Simply using ordinary scotch tape to fix SMF to the table usually provides more than enough stability in 99% of cases. When doing this, a pro tip is to tape the end of each piece of tape to itself, creating a non-sticky "handle" that makes it easy to remove and reposition.
Furthermore, if you use a polarization controller, a PBS and a power meter as shown in the video, it's easy to re-optimize the polarization if it gets misaligned for some reason. Simply adjust the paddles until the power in the port measured by the power meter is minimized, in which case the power in the other port that you are sending to the SHG crystal must be maximized.
Hope this helps. Feel free to let me know if you have additional questions!
This is great. We'll give it a try and thanks for the PRO TIP. @@yourfavouriteta
@@w8ryanb No problem. Good luck with your experiment and let me know how it goes. I plan on publishing a video explaining the intuition behind phase matching in nonlinear processes, which you may find interesting, so stay tuned!
What software are you using?
It's the software that came on a CD with the Thorlabs IPM5300 module. This is a legacy device from around 2006 but the manual is still available on Thorlabs' website.
@@yourfavouriteta Thank you.
What type of optical polarizer will keep polarization (circular).
The easiest way to remove light that is, for example, left-hand circularly polarized is to place a quarter-wave-plate in front of a regular polarizer and another one after.
Here is the idea: First, align the polarizer at a 45deg angle compared to whatever x-axis you choose, so that E-field vectors pointing in that 45deg direction are transmitted and those at a -45 deg angle are removed.
The QWP in front of this polarizer will introduce a π/2 phase shift between the x- and y-components of whatever light enters. Thus, Right Hand Circular light becomes +45 deg polarized and is let through, while Left Hand Circular Light becomes -45deg polarized and is removed (or maybe the other way around, but try checking this yourself as an exercise).
The last QWP can then introduce another phase shift and make the light circular again. If you specifically want it to be RHC again, you can place a half-wave-plate in front of the final QWP and use it to rotate the polarization appropriately.
Hope that helps!