Abstract
The absolute two-photon absorption coefficients of uv-transmitting materials have been measured using well-calibrated single picosecond pulses, at the third and fourth harmonic of a mode-locked YAlG:Nd laser system. Two-photon absorption coefficients of the order of cm/MW were measured for alkali halides, and cm/MW for harmonic-generating crystals. In materials with band gap greater than , 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 multiphoton absorption on the conversion efficiency of harmonic generating crystals and on the breakdown of uv window materials is also discussed.
- Received 10 November 1977
DOI:https://doi.org/10.1103/PhysRevB.17.4620
©1978 American Physical Society