ISSN Print: 1049-0787
ISSN Online: 2375-0294
Indexed in
NONLINEAR PHENOMENA IN LASER-MATERIAL INTERACTIONS
ABSTRAKT
For decades, the majority of laser-materials processing was done with lasers that employed classical (or linear) light-matter interactions. Such interactions are well understood, readily modeled, and are used for a very wide variety of laser-materials processing. In the past decade or so, however, high-power, short pulse lasers have become commercially available that can initiate several non-classical (or non-linear) light-matter interactions in materials. With such lasers the incident radiation intensity can exceeds one or more critical values, which can initiate alternative radiation absorption mechanisms that can substantially alter the fundamental radiation absorption - hence energy distribution - in a material. Such phenomena, in turn, can substantially alter the temperature history, heat transfer, thermal properties, and behavior of the material interacting with the radiation, resulting in exciting new opportunities for both basic research and practical applications. This article highlights several non-linear phenomena that can become important during short-pulse high-power laser material interactions: avalanche ionization, saturable absorption, multiphoton absorption, the optical Kerr effect, and plasma defocusing. From an applied perspective, the advantages of using non-linear laser-material interactions for materials processing are substantial, and include negligible thermal damage to the workpiece, an extremely wide range of material processing capability, and sub-micron and volumetric feature capabilities. In terms of research, non-linear laser-material interactions represent a fertile area with considerable research opportunities to characterize and clarify the nature of these interactions, while also developing innovative new ways in which to employ these mechanisms for novel processing capabilities. Applications for the understanding and deployment of non-linear laser-material interactions using high power lasers include precision laser micromaching, biological applications, diagnostic and assay capabilities, and development of unique thin-film materials.