Knowledge Bank

The phenomena of stimulated Raman scattering (SRS) and frequency mixing in nonlinear optical crystals can potentially be used to great advantage in molecular spectroscopy investigations, since they result in the production of pulsed, intense, coherent, collimated radiation at discrete wavelengths. In most instances, SRS has been produced by using either 6943\AA ruby laser or $1.058\mu$ neodymium laser radiation. On the other hand, the so-called second harmonic radiation of these laser sources, at 3472\AA and 5290\AA, respectively, would provide a more useful set of discrete SRS wavelengths, i.e., ``laser-like'' radiation in the ultraviolet spectral region where the electronic absorption bands of a great number of molecules are located. However, few experiments of SRS involving the second-harmonic of giant-pulsed laser radiation have been reported. The reasons for this are discussed and experimental techniques which can be used to overcome some of the limitations inherent in the production of SRS spectra of second harmonic radiation are described. In addition, recent experimental $results,1-4$ which are pertinent to the production of coherent radiation at discrete wavelengths throughout the UV, visible and IR spectral regions are reviewed. This work was supported in part by the Air Force Avionics Laboratory, Research and Technology Division under Contract No. AF 33(615)-3669, and NASA/Electronics Research Center under Contract No. NASI-2137, and Edgewood Arsenal, U.S. Army, under Contract No. DA-04-495-AMC-1218(A).