Nanostructured Silver/Polystyrene Composite Film: Preparation and Ultrafast Third-Order Optical Nonlinearity

Surface-modified silver nanoparticles with various sizes, synthesized by water-in-oil micro-emulsion, were incorporated into polystyrene (PS) to form transparent nanocomposite films through solution-mixing and static-casting. It was found that the Ag nanoparticles could be re-dispersed well in the polymer matrix by using chloroform as a solvent due to a strong interaction between Ag and chloroform. XPS analysis suggested that there is no obvious interaction between nanosilver and the polystyrene matrix. The third-order nonlinear optical susceptibility of Ag/PS nanocomposite films is around 10-esu and increases with increasing particle size, as measured by the time-resolved femtosecond optical Kerr effect experiment at a wavelength of 830nm. The results demonstrate that the present fabrication approach can effectively tailor the structure and properties of the nanocomposites.

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Study on the Third-Order Nonlinear Optical Properties of Cd2+ Ion Doped Zns/PVP Nanocomposite FilmsB. Suresh1, S. Ramachandran1 and G. Shanmugam2

10.21203/rs.3.rs-592579/v1 ◽

2021 ◽

Author(s):

B. Suresh ◽

S. Ramachandran ◽

G SHANMUGAM

Keyword(s):

Nanocomposite Film ◽

Nonlinear Optical ◽

Blue Emission ◽

Optical Nonlinearity ◽

Device Fabrication ◽

Nanocomposite Films ◽

Zns Nanoparticles ◽

Third Order ◽

Nonlinear Optical Susceptibility ◽

Cd Doping

Abstract Cd2+ ion doped ZnS/PVP nanocomposite films have been prepared using in-situ chemical method. XRD studies confirm the cubic structure of ZnS for all the films and the nanocrystallite size of ZnS is found to varying from 3.82 to 4.07 nm with Cd doping. The morphology of the films has been analyzed using SEM micrograph which shows the mono dispersion of ZnS nanoparticles in PVP matrix. The interaction between ZnS nanoparticles and PVP polymer matrix has been discussed using FTIR spectra. Optical absorption spectra of the films reveal the blue shift on the absorbance onset with the comparison of bulk ZnS and the estimated optical band gap energy decreases with increasing the concentration of Cd dopant. Photoluminescence spectra show a blue emission peak for all the films. The Z-scan results of three samples show a reverse saturation absorption process in open Z-scan experiment and self-focusing behavior in closed Z-scan experiment. Both ZnS/PVP and Cd2+ ion doped ZnS/PVP films exhibited the large optical nonlinearity and the value of nonlinear refractive index (n2), nonlinear absorption coefficient (β), third-order nonlinear optical susceptibility (χ(3)) and figure of merit (FOM) increase with Cd doping. The estimated n2, β, χ(3) and FOM values were found to be high for 6 mol% Cd doped ZnS/PVP nanocomposite film and they are about 1.771⋅10− 10 m2 W− 1, 4.148⋅10− 3 mW− 1, 1.603⋅10− 4 esu and 9.576⋅10− 6 esu m respectively. The experimental results clearly showed that the Cd2+ ion doped ZnS/PVP nanocomposite film is a worthy candidate for the future nonlinear optical device fabrication.

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Giant enhancement of THz-frequency optical nonlinearity by phonon polariton in ionic crystals

Nature Communications ◽

10.1038/s41467-021-23526-w ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Yao Lu ◽

Qi Zhang ◽

Qiang Wu ◽

Zhigang Chen ◽

Xueming Liu ◽

...

Keyword(s):

Near Infrared ◽

Optical Nonlinearity ◽

Ionic Crystals ◽

Nonlinear Optical Susceptibility ◽

Time Resolved ◽

Light Coupling ◽

Tremendous Progress ◽

Fundamental Research ◽

Ionic Contribution ◽

Time Resolved Imaging

AbstractThe field of nonlinear optics has grown substantially in past decades, leading to tremendous progress in fundamental research and revolutionized applications. Traditionally, the optical nonlinearity for a light wave at frequencies beyond near-infrared is observed with very high peak intensity, as in most materials only the electronic nonlinearity dominates while ionic contribution is negligible. However, it was shown that the ionic contribution to nonlinearity can be much larger than the electronic one in microwave experiments. In the terahertz (THz) regime, phonon polariton may assist to substantially trigger the ionic nonlinearity of the crystals, so as to enhance even more the nonlinear optical susceptibility. Here, we experimentally demonstrate a giant second-order optical nonlinearity at THz frequency, orders of magnitude higher than that in the visible and microwave regimes. Different from previous work, the phonon-light coupling is achieved under a phase-matching setting, and the dynamic process of nonlinear THz generation is directly observed in a thin-film waveguide using a time-resolved imaging technique. Furthermore, a nonlinear modification to the Huang equations is proposed to explain the observed nonlinearity enhancement. This work brings about an effective approach to achieve high nonlinearity in ionic crystals, promising for applications in THz nonlinear technologies.

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