Comparison of forward and backward second harmonic generation in poling and non-poling area of PPLN

Autor: Yu-Yi Tzeng, 曾鈺懿
Rok vydání: 2010
Druh dokumentu: 學位論文 ; thesis
Popis: 99
In recent years, laser has been wildly used in many applications. Because of the lack of laser source in certain wavelength, generating new light source in nonlinear materials by the quasi-phase matching technique (QPM) becomes one of the most important methods. Periodically poled crystal (PPC) is one of the most attractive materials in nonlinear optics due to its high nonlinear conversion efficiency. Good crystal structure leads to good nonlinear conversion efficiency. However, the crystal quality is only judged by observing spatial stability of the period before. There has been no study tries to give the internal micro-crystal structure information in both poling and non-poling domains of periodically poled crystals. Note that molecular structure of crystal affects second harmonic generation (SHG) signals, we choose second harmonic microscopy to observe PPC. Both the forward and backward second harmonic images are analyzed. In this study, we prove that the crystal structure is changed during poling process and also discussed the relation between the applied electric field in the process and the SHG intensity in PPLN. Furthermore, we compare the SHG performance between poling and non-poling domains in both forward and backward channels and pointed out the difference between these two domains. We believe that this study is very helpful for the improvement in fabrications of PPC in the future.
Databáze: Networked Digital Library of Theses & Dissertations