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366. LASER CAVITY: A Program to Aid in the Design of a
Four-Mirror Laser Having a Tightly Focused Beam in Two
of Its Three Segments
by Donald A. Chernoff, Department of Chemistry and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637 Tight focusing of the laser beam inside a laser cavity is necessary for applications such as continuous operation of dye lasers, acousto-optic cavity dumping, and intracavity frequency doubling. Focusing may be accomplished either with a lens or a mirror. Kogelnik, Ippen, Dienes, and Shank1 have discussed the properties of astigmatic resonators containing one off-axis focusing mirror. A key feature is the fact that the spacing between the mirrors at the tightly focused segment of the cavity is very critical. In designing a laser cavity to suit the requirements of the components placed at the beam focus, it is convenient to express performance criteria in terms of the confocal parameter in the various regions of the cavity. The confocal parameter, b, is determined by the construction parameters: mirror curvatures, spacings and angles of incidence. The radius of the beam at the focus is wo = (lb/2p)1/2 , where l is the wavelength of the light.2,3 The evaluation of trial cavity configurations using the formulas given by Kogelnik and co-workers is easy for a cavity containing one tight focus, but is tedious for the cases of two or more foci. The LASER CAVITY program is arranged for the two foci case. Users interested in more complicated situations would need to add a few statements to the STABIL and MAIN routines. _________ References: 1. H. W. Kogelnik, E. P. Ippen, A. Dienes, and C. V. Shank, IEEE J. Qu. Elec., QE-8, 375(1972). 2. A. Yariv, Introduction to Optical Electronics (New York: Holt, Rinehart and Winston, 1971). 3. S. E. Harris and R. W. Wallace, "Focusing and Collimation of Gaussian Laser Beams," Application Note No. 5, Chromatix Inc. (1975). _________ FORTRAN IV (IBM) Lines of Code: 264 Recommended Citation: D. A. Chernoff, QCPE 11, 366 (1978). |