Hacker News Reader

Comment by Doxin | Hacker News Reader

Am I reading right that there's a direct interaction between magnetism and optical polarization? I know that light polarization is a pretty wacky topic to start with, but having magnets in the mix makes it seem unlikely amounts of wacky to me!

Anyone got any reading on the topic?

View on HN

Yep, the Faraday Effect!

The sibling comment has a link to the Wikipedia page, yet for a quick video explanation and demonstration Applied Science's video on the Faraday Effect was fantastic. It demonstrates it, explains some use cases, and also goes into how the material the light is passing through affects the strength of the magnetic induced rotation.

https://www.youtube.com/watch?v=XhU-nNiAgtI

That sounds very wrong. Not a physicist, but light does not interact with magnets, or you need to get into the superconducting strength levels before it does.

https://en.m.wikipedia.org/wiki/Optical_rotation

It seems the optical rotation happens due to molecular structure of specific materials.

Edit, found this: https://en.wikipedia.org/wiki/Faraday_effect

So a specific material plus magnetic field is needed. But still not sure how strong of a field is sufficient.

For more details on this specific application these pages might be more relevant:

https://en.wikipedia.org/wiki/Optical_isolator

https://en.wikipedia.org/wiki/Faraday_rotator

Magnet there is probably used as an isolator. The laser can only go out,but not come back.( yes, there will be laser coming back from reflection, which also interrupt the operation of the source laser.

Reply on news.ycombinator.com