Abstract

The fabrication of precision optics is critical for a wide range of applications, including biosensors, virtual and augmented reality, medical imaging, and micro-electronics. However, it is challenging to meet the demands of these applications with conventional chemical and mechanical fabrication methods, as they can introduce chemical waste, mid-spatial-frequency errors, and subsurface damage that degrades image quality. Femtosecond lasers have emerged as a promising alternative, offering fast, non-contact, and chemical-free machining with single digit nanometer precision. This thesis presents a computational model designed to investigate the interaction process between a high-intensity femtosecond laser pulse and dielectric material. A pulse propagation model is implemented to simulate material response, predicting time and intensity dependent optical properties. The model incorporates the Keldysh theory of photoionization to accurately predict the generation of free electrons under laser irradiation, enabling precise estimates of material removal and crater formation. The predicted crater morphology shows strong agreement with experimental observations. To further understand the thermal effects of laser processing, a two-temperature model is implemented to simulate heat-affected zones and their impact. Additionally, the model is extended to multi-pulse simulations under gigahertz burst mode operation, allowing for analysis of plasma and thermal accumulation. These insights contribute to the optimization of femtosecond laser parameters for precision optical fabrication with minimized damage and improved control.

Library of Congress Subject Headings

Femtosecond lasers--Mathematical models; Optical instruments--Design and construction; Optical materials

Publication Date

6-2025

Document Type

Thesis

Student Type

Graduate

Degree Name

Physics (MS)

Department, Program, or Center

Physics and Astronomy, School of

College

College of Science

Advisor

Jie Qiao

Advisor/Committee Member

Pratik Dholabhai

Advisor/Committee Member

Basca Jadamba

Campus

RIT – Main Campus

Plan Codes

PHYS-MS

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