Solid-State Lasers Radiative Properties of Ruby Crystals

Solid-State Lasers Radiative Properties of Ruby Crystals 

The first optical laser, the ruby laser, was built in 1960 by Theodore Maiman. Since that time lasers have had a profound impact on many areas of science and indeed on our everyday lives. The monochromaticity, coherence, high-intensity, and widely variable pulse-duration properties of lasers have led to dramatic improvements in optical measurements of all kinds and have proven especially valuable in spectroscopic studies in chemistry and physics. Because of their robustness and high power outputs, solid-state lasers are the workhorse devices in most of these applications, either as primary sources or, via nonlinear crystals or dye media, as frequency-shifted sources. In this experiment the 1064-mn near-infrared output from a solid-state Nd YAG laser will be frequency doubled to 532 nm to serve as a fast optical pump of a raby crystal. Ruby consists of a dilute solution of chromium 3 ions in a sapphire (AI2O3) lattice and is representative of many metal ion-doped solids that are useful as solid-state lasers, phosphors, and other luminescing materials. The radiative and nonradiative relaxation processes in such systems are important in determining their emission efficiencies, and these decay paths for the electronically excited Cr ion will be examined in this experiment. 

Pumping-emission cycle for a typical four-level laser. 

In the subsequent discussion, the wavelengths of transitions are cited, as is conventional in describing laser lines. The frequency v in cm units is given by r = 10 /A, where A is the wavelength in nm. 

The output from a NdiYAG laser has a wavelength of 1064 mn, which corresponds to a photon energy that is too small for electronic excitation of most molecules. However, 

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