Spectroscopic Studies of Novel Materials for Display and NLO applications

摘要

During the grant period our research was organized into three thrust areas: Material preparation; nonlinear optical characterization; and luminescence studies on display materials. We successfully prepared, KN, KTN, SBN etc. photorefractive materials in the form of thin films using pulsed laser deposition (PLD) technique through collaboration with the professor sharing our laboratory. We also used sol-gel technique and laser-pedal crystal growth to prepare some luminescent material and Low voltage cathodoluminescent phosphors. During the period we systematically studied the ultrafast nonlinear optical response with the purpose of searching for larger third-order nonlinearity, and found significant enhancement of SBN in the form of thin film. Based on the experimental observation a charge-transferred-vibronic model was successfully developed. We also discovered valence switching by charge carriers produced in CB and captured by ions residing on the boundary surface in nanostructured materials. The study of luminescent materials for display applications was extended to SrAl2O4: CaAl4O7:Eu(3+). Eu(2+),Dy(3+), and long lifetime display materials were developed. It was found that the excitation by high Uv flux can produce higher density of electrons near the grain boundary, which may further enhance the indirect transition probability or increase energy transfer from surface states to the SA centers of the host.