Two-Photon Absorption Coefficient In Relation To The Typical Pulse Models Of Laser

The two-photon absorption (TPA) coefficient (beta) relating to pulse models of laser is theoretically studied based on the nonlinear absorption equation. An expression of nonlinear energy transmission is obtained, in which a factor (g) is introduced to describe the beta deviation resulting from the pulse profile of laser. The relative deviation can be then expressed as (1/g - 1)% for comparing beta obtained based on other pulse models of laser with beta(0) based on the rectangular one. The values of g factor and the deviation of some typical Ultra-short pulse models used nowadays are also calculated and presented. Our results suggest that the beta deviations from the temporal pulse shapes should not be neglected in usual nonlinear transmission measurement. The g factor may become a useful parameter in taking account of this deviation. (C) 2010 Elsevier B.V. All rights reserved.