I. Resonant two-proton reabsorption by exition-polaritons in cuprous chloride films ; II. Heat pulse progration across metal/sapphire interfaces ; III. Phonon focusing in piezoelectric crystals

"The work described ir. this thesis involves the study of optical ar.d thermal propterties of semicor.ductors and consists of three seperate topics. 1. Resonant two-photon absorption by exciton polaritons in CuCl ~. A study of the lineshape and intersity of the biexciton decay luminescerce reveals a two-photon reabsorption process in which the longitudinal exciton and the transverse polaritor act as resonant intermediate states. Dispersion informatior or these states at large momertum is produced and a simplified theory of the resonant resonant reabsorption process is described. 2.Heat pulse propagation across metal/sapphire interfaces. The angular dependerce of ballistic phonon propagatior ir sapphire is found to exhibit three distinct types of features. The first corresponds to mathematical singularities in the bulk phonon focusing. The second type of feature observed corresponds directions in which the phonon flux exhibts a local but nonsingular maximum. These features are termed ""precursors"" because they will transform into normal singularities if the elastic constants are modified slightly. These two types of features are readily predicted by classical elasticity theory. The third type of feature is a surface effect in which a consentration of transverse phonons near the critical cone for mode conversion from bulk transverse waves to longitudinal waves along the surface. It is found to be dependent on surface orientation and is very sensitive to surface quality. A theory by A. Every is described in which this feature is due to a longitudinal pseudo-surface wave on free or weakly bonded surfaces. 3. Phonon Focusing in Piezoelectric Crystals. The calculation of phonon focusing patterns through classical elasticity theory is extended to include the piezoelectric effect in the quasistatic limit through the use of ""stiffened"" elastic constants. Good agreement between experimental and theoretical predictions is obtained. While the effect is small fora-quartz it is dramatic for lithium niobate."

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Year dc:date

2011

Author dc:creator

• Koos, Gregory Lee

Contributors dc:contributor

• Wolfe, J.P.

• resonant two-photon reabsorption
• exciton-polaritons
• cuprous chloride films
• heat pulse propagation
• metal/sapphire interfaces
• phonon focusing
• piezoelectric crystals

Statement dc:rights

• 1984 Gregory Lee Koos

Language dc:language

en

Identifier

824805

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/25350