The broadband optical pumping of a synthetic pink ruby crystal using a flash lamp is capable of raising a substantial fraction of the chromium ions to the upper laser level. (Maiman, 1960).

Quantum Description:

After Schawlow and Townes published their paper on the possibility of laser action in the infrared and visible spectrum it wasn't long before many researchers began seriously considering practical devices. Most experts were speculating that gases would be the first to lase in the optical and infrared. It came as surprise that ruby was the first substance to produce laser action in the visible spectrum (Maiman, 1960). There was a bitter legal battle over who invented the laser (see patent wars).

Initially it was thought that broadband optical pumping would be inefficient but this was only for ions with very narrow resonances such as those in gases and plasmas. When ions are embedded in a solid, they can absorb radiation in a much wider band of wavelengths. Optical radiation of about 550 nanometers is absorbed by dilute population of Cr+3 ions lightly doped in a corundum crystal matrix (0.05% by weight Cr2O3 versus Al2O3 ) then a rapid non-thermal transition is made to a lower metastable level whose lifetime is 5 milliseconds. If the pump power exceeds a certain threshold, a population inversion can build up between the ground state and this metastable state. The laser's performance is greatly improved by enclosing it in an optical resonator.

Mechanical Description:

The first successfully optical laser constructed by Maiman (1960), consisted of a ruby crystal surrounded by a helicoidal flash tube enclosed within a polished aluminum cylindrical cavity cooled by forced air. The ruby cylinder forms a Fabry-Perot cavity by optically polishing the ends to be parallel to within a third of a wavelength of light. Each end was coated with evaporated silver, one end was made less reflective to allow some radiation to escape as a beam.

Photo-pumped by a fast discharge flash-lamp, the first ruby lasers operated in pulsed mode for reasons of heat dissipation and the need for high pumping powers. Nelson and Boyle (1962) constructed a continuous lasing ruby by replacing the flash lamp with an arclamp.

Practical Use

A short while after the initial announcement of the first successful optical laser, other labs around the world jumped on the bandwagon trying out many different substrates and ions such as rare earths like Nd, Pr, Tm, Ho, Er, Yb, Gd even Uranium was successfully lased ! Many different substrates were tried such as Yttrium Aluminum Garnet (YAG), glass (which was easier to manufacture), CaF2. As manufacturing techniques improved these lasers rapidly made the transition from the lab bench to commercial applications.

T.H. Maiman : Dr. T H Maiman with the first ruby laser

Initially, the laser was called an invention looking for a job.
- Harry Stine.


  1. Maiman,T.H.: 1960, Nature, 187, 493.
  2. Nelson,D.F., Boyle,W.S.: 1962, Appl.Opt. 1, 181.
  3. Schawlow and Townes : ...

Ruby Lasers

Laser Medicine


Laser History