Accession Number : ADA050379


Title :   Absolute Two-Photon Absorption Coefficients in UltraViolet Window Materials


Descriptive Note : Final technical rept. 1 Jun 1975-30 Sep 1977


Corporate Author : HARVARD UNIV CAMBRIDGE MA DIV OF APPLIED SCIENCES


Personal Author(s) : Bloembergen, N ; Blake, J


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a050379.pdf


Report Date : Dec 1977


Pagination or Media Count : 51


Abstract : The absolute two-photon absorption coefficients of u.v. transmitting materials have been measured using well-calibrated single picosecond pulses, at the third and fourth harmonic of a mode locked Nd:YAG laser systems. Two-photon absorption coefficients of the order of .001 cm/MW were measured for alkali- halides, and .0001 cm/MW for harmonic generating crystals. In materials with band gap greater than 2 h-bar omega, no nonlinear absorption could be observed. Calculations based on the Keldysh theory with one adjustable parameter agree quite well with the experimentally observed dispersions in the two-photon absorption coefficients. The effect of multi-photon absorption on the conversion efficiency of harmonic generating crystals and on the breakdown of u. v. window materials is also discussed. (Author)


Descriptors :   *ABSORPTION COEFFICIENTS , *TWO PHOTON ABSORPTION , *ULTRAVIOLET OPTICAL MATERIALS , ALKALI METAL COMPOUNDS , DEGRADATION , HALIDES , LASER BEAMS , MODE LOCKED LASERS , NEODYMIUM LASERS , NONLINEAR ANALYSIS , PULSES , QUARTZ , RADIATION DAMAGE , SAPPHIRE , ULTRAVIOLET RADIATION , WINDOWS , YAG LASERS


Subject Categories : Optics


Distribution Statement : APPROVED FOR PUBLIC RELEASE