Seongmin Ma

Optical nonlinearities of Au nanoparticles and Au/Ag coreshells

Au nanoparticles exhibited both negative and positive nonlinear absorptions with ground-state plasmon bleaching and free-carrier absorption that could be origins of the saturable and reverse-saturable optical properties. Au/Ag coreshells displayed only positive nonlinear absorption and reverse-saturable optical properties as a function of excitation intensity at the edge of surface-plasmon resonance, which implies no ground-state plasmon bleaching and the existence of two-photon absorption.

Large Resonant Third-order Optical Nonlinearity of CdSe Nanocrystal Quantum Dots

Resonant third-order nonlinear optical susceptibility and hyperpolarizability of CdSe nanocrystal quantum dots were revealed to be ~2.6×10 -20 - 2.7×10 -19 m 2 /V 2 and ~2.2×10 -40 m 5 /V 2 by using nanosecond degenerate four-wave mixing at 532 nm. The large nonlinearity of the CdSe nanocrystals is attributed to the resonant excitation and multiple nonlinear optical processes.

Third-order Optical Nonlinearities of Singlewall Carbon Nanotubes for Nonlinear Transmission Limiting Application

Third-order nonlinear susceptibility of single wall carbon nanotubes thin film was measured to be ~1.4u10 -16 m 2 /V 2 . The nonlinear transmission limiting threshold of carbon SWNT was ~20 MW/cm 2 with visible and nanosecond laser excitation.

Ultrafast Time-Resolved DFWM of CdTe Quantum Dots in Toluene

Ultrafast third-order nonlinear dynamics in CdTe quantum dots at room temperature have been investigated using a degenerate four-wave mixing at ~775 nm. The effective third-order nonlinear optical susceptibility and the intrinsic dephasing time in CdTe QDs were estimated to be ~4.39×10-22 m2/V2 and ~675 fs, respectively.

Cubic Nonlinear Optical Properties of Ag Nanoparticles and Ag/Au Coreshells

Cubic nonlinear optical properties of spherical Ag nanoparticles (NPs) and Ag/Au coreshells have been investigated using a polarization-resolved degenerate four-wave mixing technique in a near resonant region. The averaged second hyperpolarizabilities of Ag NPs and Ag/Au coreshells were estimated to be ~8.12×10-38 m5/V2 and ~1.77×10-38 m5/V2, and ~1.28×10-39 m5/V2 and ~9.41×10-40 m5/V2 for parallel DFWM and orthogonal DFWM, respectively.

Cubic nonlinearity and hyperpolarizability of gold nanometals

The hyperpolarizabilities of Au nanoparticles and Au/Ag coreshells were estimated to be ~2times10^-41- ~2times10^-40 m⁵/V² with large electronic polarization processes.

Polarization-resolved cubic nonlinearity and optical power limiting of highly porous silica nanoaerogels

A highly porous silica nanoaerogel has a strong optical power limiting behavior with a negative nonlinear property. The third-order nonlinear susceptibility of silica nanoaerogels was estimated to be ~9.6 x 10^-19 m² / V² (~6.9 x 10^-11 esu) from DFWM measurements.

Slow and Fast Light Using Stimulated Rayleigh-Wing Scattering

Stimulated Rayleigh-Wing Scattering has been found to be a perfect way for group velocity controlling. The velocity of a pulse can be exactly controlled by tuning the wavelength and intensity of a strong CW beam.

Nonlinear Optical Properties of Nanostructured Supramolecular Organic Semiconductor

Resonant third-order optical susceptibility and hyperpolarizability of donor polymer in chloroform were revealed to be ~2.5 − 9.1 × 10−20 m2/V2 and ~8.6 × 10−42 m5/V2 by degenerate four-wave mixing in nanosecond scale at 532 nm, which was attributed to the resonant enhancement.

Controlling of the Group Velocity Using Third-Order Nonlinearity

Third-order nonlinearity of optical material has been found to be very useful for group velocity controlling. The velocity of a pulse may be changed by tuning its intensity or using an extra CW pump.