I don’t know about you, but when I think of lasers, I think of boxes on heavy, stabilized tables. Inside the boxes, the optical elements are mounted on stabilized mounts and everything is generally held as solidly in place as possible. The one thing that you generally don’t do is give a laser a good shaking. Unless it has already stopped working, in which case, have at it… preferably with a hammer.

Finding a paper that demonstrated a laser with better performance when it was being shaken compared to when it was held came as a bit of a shock.

The reason why the idea of shaking a laser is so shocking to me is that the lasers I am used to working with have optical elements that need to maintain a precise alignment with respect to one another. Temperature changes, vibrations, shaking, and “thumping the box to fix it” are all really bad ideas. But of course not all lasers are like this.

The laser in your laser pointer, CD, DVD, and Blu-Ray players are all monolithic devices. That is, they are made from a single piece of material, or materials, that are deposited on one another. You can obviously shake a laser pointer (much to the delight of cats), but this capability doesn’t scale. If you were to shake a laser pointer with acoustic waves that had a wavelength about the same size as the device (in the GHz range), then I would expect that things would probably go wrong rather quickly.

In most cases, at least. A group of researchers from Germany and Russia have now made a laser that works better when it is shaken. The reason why this occurs lies in the peculiar nature of the laser used by the researchers.

The laser that the researchers worked with was made from quantum dots (see side bar) embedded in a semiconductor material that had mirrors deposited on either side of it. This means that the distance between the two mirrors was extremely short. The researchers don’t state how big the distance was, but from the figures, I estimate that it wasn’t much longer than eight micrometers. For comparison, the wavelength emitted by the quantum dots was around 900nm.

(via A laser that works better shaken, not stirred)