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Nonlinear refraction and saturable absorption in Au:BaTiO3 composite films
Weitian Wang1, Guang Yang, Zhenghao Chen
1Laboratory of Optical Physics, Institute of Physics and Center for Condensed Matter Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100080, China.
Applied Optics
|October 7, 2003
Summary
Gold-barium titanate composite films were synthesized with embedded gold nanoparticles. Their nonlinear optical properties were investigated, showing a strong dependence on gold concentration and nonlinear susceptibility.
Area of Science:
- Materials Science
- Nanotechnology
- Optoelectronics
Background:
- Barium titanate (BaTiO3) is a well-known ferroelectric material with significant optical properties.
- Incorporating metallic nanoparticles into dielectric matrices can create novel composite materials with enhanced functionalities.
- Gold nanoparticles exhibit surface plasmon resonance, leading to unique optical responses.
Purpose of the Study:
- To synthesize Au:BaTiO3 composite thin films with embedded gold nanoparticles.
- To characterize the nanostructure and optical properties of these composite films.
- To investigate the influence of gold concentration on nonlinear optical behavior.
Main Methods:
- Pulsed laser deposition (PLD) was used to synthesize Au:BaTiO3 films on MgO (100) substrates.
- High-resolution transmission electron microscopy (HRTEM) was employed to analyze film nanostructure and gold particle size distribution.
- Z-scan measurements at 532 nm were performed to determine nonlinear optical properties.
Main Results:
- Successfully synthesized Au:BaTiO3 composite films with uniformly dispersed nanometer-sized gold particles within the BaTiO3 matrix.
- HRTEM confirmed the presence of crystal lattice fringes for both Au nanocrystals and BaTiO3.
- Nonlinear optical measurements revealed that the z-scan transmittance curves were significantly influenced by the ratio of the imaginary to the real part of the third-order nonlinear susceptibility (χ(3)), especially at high gold concentrations.
Conclusions:
- The synthesized Au:BaTiO3 composite films possess tunable nonlinear optical properties.
- The observed nonlinear optical effects are strongly correlated with the gold nanoparticle concentration and the third-order nonlinear susceptibility.
- These findings suggest potential applications for Au:BaTiO3 composite films in optical devices and nonlinear optics.