Calculations of the Frequency Dependence of Elasto-optic Constants of Infrared Laser Window Materials.
Physical sciences research papers,
AIR FORCE CAMBRIDGE RESEARCH LABS HANSCOM AFB MASS
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Stress-induced birefringence may severely degrade or limit the optical performance of infrared transmitting materials, especially in high power laser applications, Thus, prediction of this phenomenon is essential for the appropriate selection of high power IR laser window materials for numerous applications. In this report a detailed first-principles calculation of the elasto-optic, or strain-optic, constants p sub ij is carried out for the first time throughout infrared frequencies, employing a recent theory of Humphreys and Maradudin. For ionic crystals, a Born-Mayer interatomic potential is used, while for semiconductors a Morse potential is used. Two methods for obtaining the p sub ij are applied one incorporates parameters based on standard thermodynamic prescriptions, the other combines these same parameters with additional ones derived from pressure-dependent data. For both cases, the dispersions in the p sub ij, as well as in the thermal lensing parameters, are calculated throughout the IR regime for a wide variety of rocksalt- and zinc blende-structure compounds.
- Lasers and Masers