Optical Science and Engineering ETDs

Publication Date

Summer 6-22-2025

Abstract

Solid-state optical refrigeration using anti-Stokes fluorescence offers a compact, vibration-free route to cryogenic cooling. This dissertation advances ytterbium-doped yttrium lithium fluoride (Yb:YLF) refrigerators, achieving a world record payload cooling temperature of 124 K by addressing key limitations due to absorption saturation. An expanded theoretical model incorporating saturation effects enables accurate predictions of cooling performance under high pump intensities. To improve pump control, a modeling framework for astigmatic Herriott cells was developed, revealing how beam clipping and intensity impact coupling efficiency. A novel fluorescence-based thermometry method was also established, providing accurate, orientation-independent temperature sensing by overcoming reabsorption and crystal orientation. Finally, a successful monolithic refrigerator prototype with directly attached mirror coatings and a highly divergent pump beam was realized, enabling uniform absorption and efficient, compact operation. iv

Degree Name

Optical Science and Engineering

Level of Degree

Doctoral

Department Name

Optical Science and Engineering

First Committee Member (Chair)

Alexander Albrecht

Second Committee Member

Tara Drake

Third Committee Member

Payman Zarkesh-Ha

Fourth Committee Member

Markus Hehlen

Keywords

Optical refrigeration, Herriott cell, spectroscopy, absorption saturation

Document Type

Dissertation

Language

English

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