Optical Science and Engineering ETDs

Publication Date

2-1-2012

Abstract

The focus of this dissertation is to design, optimize and build an efficient high power multi kilowatt thin-disk laser system. We improve the thin-disk beam quality by eliminating thermally induced lensing and disk bowing. The characteristics and performance of a ceramic and single crystal Yb:YAG thin disk (TD) lasers are analyzed both experimentally and theoretically. We perform these experiments at room and at cryogenic temperatures. Novel composite substrate materials are explored for thermal management. Thermal and stress computations are modeled in detail using the finite element analysis COMSOL software. Geometrical and physical optics models, employing ZEMAX and other numerical techniques, are used to evaluate beam quality. Theoretical modeling results are combined to further explain physical mechanisms that influence a high power output laser beam. An analytical amplified spontaneous emission (ASE) model in thin-disk laser is developed. Experimental data includes: thermal measurements of thin-disk and output couplers; small signal gain; wavefront; spectrum; lifetime and fluorescence measurements. Most importantly, for the first time, thin-disk laser performance at room and cryogenic temperatures using a novel two phase boiling cooling system is investigated. Our unique setup allows us to directly compare the same material performance at these two temperatures. Our cryogenic results show that operating the laser as a four level system could be the key in achieving very high output power with less complicated system since there is a higher cross-section, and a fewer number of pump bounces is required. Thin-disks for cryogenic operation do not have to be as thin, which also makes it easier to manufacture them. Techniques developed in these experiments are of fundamental importance in future work related to high power solid state lasers; material science, particularly ceramic lasers, and composite materials manufacturing; and cryogenic operation lasers. A thorough and detailed design of a high power thin-disk laser supported by experimental data is presented.

Degree Name

Optical Science and Engineering

Level of Degree

Doctoral

Department Name

Optical Science and Engineering

First Committee Member (Chair)

Newell, Tim

Second Committee Member

Lester, Luke

Third Committee Member

Krishna, Sanjay

Fourth Committee Member

Malloy, Kevin

Document Type

Dissertation

Language

English

Download

Share

COinS