Full text
| |
| Author(s): |
Renato Juliano Martins
Total Authors: 1
|
| Document type: | Doctoral Thesis |
| Press: | São Carlos. |
| Institution: | Universidade de São Paulo (USP). Instituto de Física de São Carlos (IFSC/BT) |
| Defense date: | 2017-03-14 |
| Examining board members: |
Cleber Renato Mendonça;
Yara Galvão Gobato;
Francisco Eduardo Gontijo Guimarães;
Sérgio Ricardo Muniz;
René Alfonso Nome Silva
|
| Advisor: | Cleber Renato Mendonça |
| Abstract | |
Pulse shaping techniques allows the control of spectral and temporal properties of a laser beam, creating new possibilities for the study of the light-matter interaction. In this work we study the nonlinear optical properties, via ultrashort pulses, of three semiconductors; Zinc Oxide, Silicon and Gallium Nitride in three different approaches. We also discuss the consequences of phase distortion in nonlinear processes due to the discrete nature of the light modulator device. Initially, we investigated the optimization of exciton emission in a zinc oxide crystal through using a genetic algorithm; we observed that the spectral phase that optimizes the process creates a temporal pulse profile that indicates an exciton-phonon coupling in the crystal. We also studied the effect of the application of a sinusoidal phase mask, creating a pulse train, in the process of laser induced periodic surface structures in Silicon; the efficacy factor of the produced structures was controlled through the separation time between the sub-pulses and interpreted using the Sipe-Drude theory. Finally, we study the influence of pulse shaping on multi-photon absorption processes in a thin film of GaN; we found, initially, that the material exhibits an atypical nonlinear absorption coefficient. We model this behavior using rate equations and investigate its modification by applying a quadratic phase. (AU) | |
| FAPESP's process: | 12/00702-2 - Coherent Control of nonlinear processes via genetic algorithm: study of spectral phase modulation through principal component analysis |
| Grantee: | Renato Juliano Martins |
| Support Opportunities: | Scholarships in Brazil - Doctorate |