The Evolution of Surface Symmetry in Femtosecond Laser-Induced Transient States of Matter

Abstract

Gallium arsenide and other III-V materials are well known for their excellent optical and electronic properties and have led to the development of high-performance optoelectronics. Several combinations of III-V semiconductors are now being considered as potentially attractive alternatives to silicon for these applications. However, further development requires fundamental understanding of processes that govern light-matter interactions. Specifically, surface strain and ultrafast dynamics are of great interest to the optoelectronic industry.

The research of this dissertation represents an initial exploration of the factors influencing nonlinear optical responses on semiconductor surfaces. The results of this research have the potential to inform the field of nonlinear optics about which lattice behaviors are most likely to contribute to static and transient second harmonic generation (SHG). This information allows for future work to focus on the connection between SHG, dipole contributions, and interatomic potentials in semiconductors under different conditions. This research also provides information about whether strain, resonances, and subpicosecond lattice behaviors can be fit with a simple analytical solution. The results of this research reveal that an analytical fit of polarization-resolved SHG is sensitive to interatomic potential and dipole variations in all three dimensions simultaneously.