Dynamics of Femtosecond-Laser Modification of Glass

非技术描述：超短脉冲（飞秒）激光玻璃结构作为一种具有三维空间选择性的改变玻璃性能的新型制造方法正变得越来越重要。尽管这项技术已经被用于制造各种无源和有源光学器件以及芯片上的实验室组件，但人们对吸收的激光能量如何消散到玻璃中，从而导致结构变化的过程知之甚少。该项目的目的是通过实验监测飞秒激光在熔融二氧化硅中的修饰动力学，以更好地了解所涉及的机制，并确定这些机制如何依赖于激光写入参数。训练有素的研究生和本科生将是跨学科研究的资源。该项目将通过提供最先进的光学和材料表征技术的实践经验，为他们提供一个独特的机会。技术细节：提出的研究重点是实验监测飞秒激光修饰熔融二氧化硅的动力学，以更好地了解这一过程。这是通过使用许多不同的飞秒激光泵浦探测实验来完成的。在第一组实验中，确定了由飞秒激光脉冲吸收产生的初始（峰值）电子密度及其与激光写入参数（如激光波长、脉冲能量、脉冲持续时间和聚焦条件）的依赖关系。第二组实验包括测量电子密度的时间演化。一旦电子密度（或等离子体）衰减，就会产生一种热液体，然后冷却，留下永久的修饰。时间相关的拉曼测量被用来探测热液体的温度作为时间的函数，直到它完全冷却。这些实验对飞秒激光在玻璃中的修饰机理提供了重要的信息。这一发现对该技术用于光学器件制造的潜在商业化具有重大影响。该项目涉及由nsf国际材料研究所提供的玻璃新功能交流项目的外国学生和访客。

NON-TECHNICAL DESCRIPTION: Ultra-short pulse (femtosecond) laser structuring of glass is becoming increasingly important as a novel fabrication method to modify the properties of glass with three-dimensional spatial selectivity. Despite the fact that this technique has already been used for the fabrication of a variety of passive and active optical devices and lab-on-chip components, little is known about the processes by which the absorbed laser energy gets dissipated into the glass, thereby causing the structural changes. The objective of this project is to experimentally monitor the dynamics of femtosecond-laser modification in fused silica to gain a better understanding of the mechanisms involved and to determine how these depend on laser writing parameters. Highly trained graduate and undergraduate students will be the resources generated by the research in a cross-disciplinary setting. This project will offer them a unique opportunity by providing hands-on experience with state-of-the-art optical and materials characterization techniques.TECHNICAL DETAILS: The focus of the proposed research is to experimentally monitor the dynamics of femtosecond-laser modification in fused silica to gain a better understanding of the process. This is done by employing a number of different femtosecond-laser pump-probe experiments. In the first set of experiments the initial (peak) electron density resulting from the absorption of the femtosecond-laser pulse is determined as well as its dependence on laser-writing parameters such as laser wavelength, pulse energy, pulse duration and focusing conditions. The second set of experiments involves measuring the time evolution of the electron density. Once the electron density (or plasma) has decayed a hot liquid results, which then cools leaving the permanent modification. Time-dependent Raman measurements are used to probe the temperature of the hot liquid as a function of time until it has cooled completely. These experiments give important information about the mechanisms responsible for femtosecond-laser modification in glass. The findings have a major impact on the potential commercialization of this technique for optical device fabrication. This project involves foreign students and visitors through exchange programs provided by the NSF-International Materials Institute for New Functionality in Glass.