Question: how do most of your lasers work?

Euan Allen answered on 20 Jun 2016:

Hi ellie science, great question. Lasers are actually really complicated, but I will do my best below to explain a little of how they work.

The good thing about lasers is that the light they produce is very regular, bright, constant, and is at exactly the same colour all the time (or at least nearly exactly the same). This is what makes them useful for many different things.

This light is made by exciting (adding energy to) a special type of material within the laser called a laser medium. When you pass enough energy through this material then it has a very special property. When you fire a photon across the material (i.e. when you shine some light on it), then the material basically creates an exact copy of this photon, meaning you now have to photons that are exactly the same. It essentially takes the light you put in and makes exactly the same light but brighter. As this new, brighter light goes along the rest of the medium, it does the same thing over and over again, meaning you end up with a really bright light source, where all the light is exactly the same. We call this amplification via stimulated emission. And that’s basically how a laser (Light Amplification by Stimulated Emission of Radiation) works!