Ruby laser, principles

Neodymium and YAG Lasers. The principle of neodymium and YAG lasers is very similar to that of the ruby laser. Neodymium ions (Nd +) are used in place of Cr + and are often distributed in glass rather than in alumina. The light from the neodymium laser has a wavelength of 1060 nm (1.06 xm) it emits in the infrared region of the electromagnetic spectrum. Yttrium (Y) ions in alumina (A) compose a form of the naturally occurring garnet (G), hence the name, YAG laser. Like the ruby laser, the Nd and YAG lasers operate from three- and four-level excited-state processes. 

Mode-locked Nd-glass or ruby lasers have also been used to investigate hole-burning and intramolecular dynamics in molecules, as have intracavity dye laser techniques, which operate on the principle of transferring the loss of intensity at the frequency of the hole in the spectrum into the enhanced gain of a dye laser, whose broadband output overlaps that frequency. 

Although there are several different varieties of laser, we explain the principles of operation using the solid-state ruby laser. Ruby is a single crystal of AI2O3 (sapphire) to which has been added on the order of 0.05% Cr ions. As previously explained (Section 21.9), these ions impart to ruby its characteristic red color more important, they provide electron states that are essential for the laser to function. The ruby laser is in the form of a rod, the ends of which are flat, parallel, and highly polished. Both ends are silvered such that one is totally reflecting and the other partially transmitting. 

The principle of laser action was first demonstrated in 1960 by Maiman. This first system was a solid-state laser a ruby crystal served as the active element, and it was pumped with a flash lamp. With this report of laser action, the main concepts upon which solid-state lasers are based became established (see Fig. 1). The idea of optically pumping the laser rod was realized, as well as the use of an impurity-doped solid as the laser medium. Lastly, the concept of a laser resonator, as adapted from the work of Townes and Schalow, was experimentally demonstrated. Much of this article is essentially an exposition of the extensive techni-... 

Chromium doped alumina, or ruby, is needless to say, a beautiful gemstone and known as the first solid-state laser in history. It is also a material of central importance to high pressure science since the ruby pressure gauge using its fluorescence lines is particularly popular in the diamond anvil cell (DAC) experiments. The electronic structure of ruby has been studied extensively based on the ligand-field theory with some additional parameters such as the trigonal-field parameter or the spin-orbit interaction parameter . However, the reports on the first-principles calculation of the multiplet structure of ruby are rather limited . The electronic structure of a-A]2 03 V + has also been studied in details based on a similar semiem-pirical approach . ... 

---