A Check Valve for Light

By Anupum Pant

Here’s a cool effect you can achieve with just light, olive oil and a few turns of copper wire (or really strong magnets with a larger section of the magnetic field where the magnetic field lines are parallel). This is called the Faraday effect and the physics of it is complicated to be explained on a blog. Not that I know how it exactly works, but it still is cool to just watch a stream of light get influenced by nothing but just a strong magnet!

One interesting application of this effect is faraday rotator, or basically check valve for light – that is to say, a device through which light passes in one direction and not in the other. So, it is transparent if you look at it from one side and opaque from the other side. The video explains this too…

Faraday rotation is an example of non-reciprocal optical propagation. Unlike what happens in an optically active medium such as a sugar solution, reflecting a polarized beam back through the same Faraday medium does not undo the polarization change the beam underwent in its forward pass through the medium. This allows Faraday rotators to be used to construct devices such as optical isolators to prevent undesired back propagation of light from disrupting or damaging an optical system.

Leave a Reply

Your email address will not be published. Required fields are marked *