• Question: How does a laser work?

    Asked by eagle eye thurst to Ian on 13 Mar 2015.
    • Photo: Ian Sandal

      Ian Sandal answered on 13 Mar 2015:


      Depending on the type of laser the work in slightly different ways, but all follow the same principle of using electricity to release light energy.

      For the type of lasers I work on (called Semiconductor lasers) this works by putting a voltage over the laser (a bit like connecting it to a battery). This electrical voltage is then used to give energy to electrical charges (particles called electrons). This energy causes them to become excited and move to a high energy level, after a very short time (normally millionths of a second) these particles will relax back to their normal state and give off the extra energy as light. This makes a basic laser.

      To make it more advanced we control the motion of the electrons so that they all gain and loose energy at the same place creating a brighter beam. We further improve the efficiency by using mirrors so that the light bounces back and forth many times (millions of times) before being emitted. This increases the power of the beam.

      Other types of lasers work in similar ways but excite atoms or gas molecules instead of electrons.

Comments