Happy birthday laser

The "solution looking for a problem", as it was called at the time of its invention, is now 48 years old. On the 16th of May 1960, Theodore Maiman used a high power flashlamp to optically pump a ruby rod, either end of which was partially coated with silver, to produce the world's first working laser.

Charles Townes and Arthur Schawlow had begun much of the theoretical work that inspired Maiman, years before. They called such a device an optical maser, because it was the optical equivalent of its predecessor which produced a coherent beam of microwaves. Maiman did not achieve laser action in the way they had theorised, however, instead producing light emission through the relaxation of electrons to their lowest energy (ground) state from a higher energy state, rather than between two intermediate high energy states. This first laser produced pulsed emission in the red part of the visible light spectrum and demonstrated the capability of lasers to produce a narrow beam of coherent light of a single wavelength.

It wasn't long before lasers were solving a growing number of problems and finding applications in all sorts of areas from medicine to entertainment. Today we find them in CD players, supermarket checkouts and on the factory floor as industrial cutting tools. Lasers have also played a huge role in the growth of the internet and telecommunications, responsible for transmitting data across vast distances using fibre optics.

The fact that Maiman's original paper, submitted to Physical Review Letters, was rejected, might be of some comfort for those researchers amongst you who are indulging in a bit of free thinking and whose "blue sky research" remains similarly unappreciated. Go ahead and build your solution; there may one day be a problem in need of it.