Laser energy deposition in insulators

Abstract

The knowledge of the mechanisms of energy transfer from laser radiation into optical materials plays an important role both for laser induced processing and the diminishing of the absorption to prevent laser damage. The theory of photon energy deposition into solids is reviewed for optical wide gap materials with emphasis on nonlinear effects. Beside the intrinsic mechanisms acting in the bulk of an ideal solid extrinsic effects are discussed which are governed by the real structure. The role of field strength enhancement due to the interference of the coherent radiation in layered structures is considered. Taking into account the balance equations of energy and charge density a coupled system of partial differential equations may be derived describing the energy transport in an effective two level system up to the heat diffusion. Some feedback mechanisms like avalanche ionization or explosive heating will be discussed.