A laser that likes a good shake

13 Jan

In general, lasers are not like old television sets: a good whack does not make a laser miraculously work better. Lasers (at least big lasers) take a lot of careful alignment to get working, so whacking, shaking, and leaning on are all out of the question. If you are being trained in a new lab, you will probably hear a lot of “no-touchy” around the laser mountings.

Some scientists in Russia, however, have created a laser that likes a good shake. The laser works by using mirrors to direct light at quantum dots, causing them to emit. The problem is that the quantum dots aren’t always in the state you need them to be in to emit light of the correct wavelength. This is where the shaking comes in. Scientists found that if they exposed quantum dots to sound waves, the properties of the dots shifted in a way that caused them to spend more time in the state that emitted at the correct wavelength. Quantum dots are perfect for this, as their electrons are willing to hang out in an excited state long enough for the sound waves to affect their properties before emitting a photon. The laser with the sound waves had a power 200 times better than without, which is pretty huge. Cool.

Article here.

Still curious? Here’s a bit more info about quantum dots: Quantum dots are tiny bits of matter with special properties. First you need to know about excitons. Excitons are basically an electron and the hole where that electron wants to go, together in a bound state. They are electrically neutral quasi-particles that exist in insulators and semiconductors. Quantum dots’ excitons are confined in all spatial dimensions. The result is a tiny bit of matter that acts (electrically) a bit like a bulk semiconductor and a bit like a single particle. Quantum dots are being researched all over the scientific world nowadays, from lasers and solar cells to quantum computing.