Optical ring resonator

Imagine you have a really cool toy - a circle that lets light go round and round it, like a race car track for light! That's what an optical ring resonator is - a tiny circle made of a special material that can trap light inside and make it race around in circles.

The important thing about this toy is that the circle is made so that the light can only go around it at very specific speeds. This is kind of like how you can only go a certain speed on a merry-go-round, or else you might fall off! Because the light can only go at certain speeds, it bounces off the walls of the circle and keeps going around and around, kind of like how a pool ball bounces off the walls of a pool table.

Scientists and engineers love playing with these optical ring resonators because they're super useful! They can use them to do all sorts of things, like make really sensitive sensors. For example, if you shine a laser beam into the circle and measure how the light behaves as it bounces around, you can tell if there's something tiny nearby - like a virus or a molecule - because it will change the way the light moves.

So basically, an optical ring resonator is a fancy toy that lets scientists and engineers play with light in really neat ways!