Small Grants for Exploratory Research: Femtosecond Pulsed Laser Machining of Chemical Vapor Deposition (CVD)-Diamond

本文将研究一种新型飞秒脉冲准分子激光加工技术用于化学气相沉积（CVD）金刚石薄膜精密加工的可行性。飞秒脉冲激光烧蚀金刚石与目前使用的纳秒或更长的脉冲激光烧蚀有很大的不同，因为飞秒脉冲激光烧蚀能够提供极端的强度和更大的吸收深度/热扩散距离比。飞秒激光器可以提供一种全新的激光-金刚石相互作用光谱，可以改变烧蚀产物的动力学（能量和质量分布）、粒子发射的性质（电离、中性等）和相关现象，即等离子体形成和冲击传播。因此，将有更大程度的被去除的材料的雾化，减少烧蚀的热成分，没有团簇和颗粒在加工表面，和更小的可能性，金刚石转变为石墨。这些影响最终使所提出的加工技术成为一种高精度、无污染、省时的加工工艺，用于加工过程中需要低体温的凹凸不平的cvd金刚石薄膜。预计这种新型激光加工方案不仅将完善现有的激光加工技术，而且将超越所有其他金刚石微加工技术，并且在薄膜沉积等其他研究领域产生新的应用。

9504102 Molian The feasibility of a novel femtosecond pulsed excimer laser processing technique for precision machining of chemical vapor deposition (CVD)-diamond films will be investigated. Femtosecond pulsed laser ablation of diamond is expected to be significantly different from that of currently practiced nanosecond or longer-pulsed laser ablation because of its capability to provide extreme intensities and larger absorption depth/thermal diffusion distance ratios. Femtosecond lasers can offer an entirely new spectrum of laser-diamond interactions that can alter dynamics of ablation products (energy and mass distribution), nature of particle emission (ionized, neutral, etc.) and associated phenomena namely plasma formation and shock propagation. Consequently, there will be a greater degree of atomization of material to be removed, reduced thermal component of ablation, absence of clusters and particulates on the machined surfaced, and less probability for the transformation of diamond to graphite. Such effects ultimately lead the proposed machining technique to be a high precision, contamination-free, time efficient procedure for craggy CVD-diamond films that requires low bulk temperature during machining. It is anticipated that this novel laser processing scheme will not only refine the existing laser-processing techniques but also surpass all other diamond micromachining techniques and, additionally, generate new applications in other areas of research such as deposition of thin films.