One- and Two-Temperature Models in Solids Under Laser Pulse Irradiation Which Effectively Present as Two-Photon Absorption Coefficient Anisotropy
M. Nemtanu, G. Craciun, E. Manaila, M. Oane, M. Brasoveanu, C. Oproiu, D. Martin and D. Ighigeanu
In this paper we have developed a semi-analytical model to study the temperature distributions in infra red (IR) optical materials heated by laser pulses. Our model takes into account two-photon absorption and calculations are based on a three-dimensional model of heat diffusion in solids using the integral transform method. We found out that the rigorous semi-analytical expression of the thermal field when one considers both one and two-photon absorption. The model is valid for any laser-solid system whose interaction can be described by the generalized Beer- Lambert law. Specific results are presented for an application of the model to GaAs sample. We discovered that two-photon absorption can produce detectable temperature variation. The main goal of the present paper was to correlate the thermal field with the two-photon absorption anisotropy.
Keywords: Heat equation, nonlinear optical materials, laser pulses, multi-photon absorption, two-photon absorption, two-temperature model