I Less known electric/magnetic interactions with light

[Malamala]

Hello! I recently came across the Hanle effect, which is a reduction or increase in the polarization of the emitted light from an ensemble of atoms as a function of an externally applied magnetic field. Not so long ago I heard about the Faraday effect which is a rotation of the polarization of the light passing through an ensemble of atoms as a function of an external magnetic field (and it seems like there is a version for the case of an external electric field, too). I haven't learned about these in my undergraduate EM or QM class and they are not something one can easily came across by chance (at least not the Hanle effect). I was wondering if there are other interesting effects like these where the light interacting with some atoms in the presence of some external field (or anything) changes some of its properties in a measurable way. Thanks!

 

[tech99]

There s the Kerr effect, polarisation rotated in some materials (such as Nitro benzene) as a result of an electric field.

 

[berkeman]

I was wondering if there are other interesting effects like these where the light interacting with some atoms in the presence of some external field (or anything) changes some of its properties in a measurable way.

https://startingelectronics.org/beginners/components/LCD/LCD_2x16.jpg

Spoiler

https://www.j-display.com/english/technology/lcdbasic.html

 

[artis]

@Malamala basically all LCD displays work that way as @berkeman pointed out. One takes a thin glass sheet, applies some chemical processes and deposits a thin film transistor aka TFT structure atop the glass, each transistor forms a pixel, and can be controlled by the thin deposited trace wires coming out the sides of the LCD panel. Special liquid crystal are sandwiched in the panel and so whenever a electric field is applied across the pixels they either let light through or block it and all of that is done by pure 90 degree rotation of it. That;s why you have a polarizer filter between the backlight of the panel and the glass TFT structure of the panel.

 

[Malamala]

There s the Kerr effect, polarisation rotated in some materials (such as Nitro benzene) as a result of an electric field.

Thank you!

 

[tech99]

Also have a look at the Pockels Effect and the Pockels Cell. https://en.wikipedia.org/wiki/Pockels_effect
It is a similar but distinct phenomenon to the Kerr Effect.

 

[tech99]

Also look at the action of the Ionosphere on radio waves, in particular the way that a plasma in a magnetic field displays absorption resonances, polarises the radiation and has varying refractive index.
And of course, the free electrons in metals exhibit plasma resonance, giving the metal a colour.