SungSoo Jung

Distortions in Z-scan spectroscopy

The sample imperfection induced distortions in the closed Z-scan curve are analyzed. It is found that both the magnitudes of the peak and valley transmittances and the shape of the curve are distorted significantly by the inhomogeneous thickness, the nonuniform nonlinearity, and the curved surfaces of the sample. The results suggest that the I-scan method is a more practical choice for the measurement of the third-order nonlinear susceptibility of an inhomogeneous sample.

Large pure refractive nonlinearity of nanostructure silica aerogel

The nonlinear refraction coefficient of silica aerogel was estimated to be ∼−1.5×10−15 m2/W (∼−3.67×10−9 esu) with a signal-beam z-scan spectroscopy. The third-order nonlinear refraction coefficient of nanostructure silica aerogel was almost five orders larger than the nonlinear refraction (χ3) of bulk material. The large nonlinear refraction with high nonlinear figure of merit is an ideal optical property for nonlinear optical applications.

Time-resolved and temperature-dependent photoluminescence of ternary and quaternary nanocrystals of CuInS2 with ZnS capping and cation exchange

Time-resolved and temperature-dependent photoluminescence (PL) spectroscopy of ternary compound copper indium disulfide (CuInS2, or CIS) core materials, CIS/ZnS coreshells, and quaternary compound ZnCuInS2 (ZnCIS) revealed their optical properties with spectral, temporal, and thermal characteristics, which were closely linked to surface-related recombination, and shallow or deep defect-related donor-acceptor transitions. The PL peaks of semiconductor nanocrystals (SNCs) with sizes near Bohr radius displayed at ∼775 nm for CIS, ∼605 nm for CIS/ZnS, and ∼611 nm for ZnCIS. The spectral blue shift and spectral narrowing with CIS/ZnS and ZnCIS are assigned to the increased spatial confinement and surface regularity with the etching of core materials. Both the shorter lifetime at surface-trapped states or interface states and the longer lifetime at intrinsic defect-related states of CIS, CIS/ZnS, and ZnCIS SNCs were widely distributed across the entire PL spectral region. The surface or interface-trapped electr...

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.

Spontaneous regression of small cell lung cancer

Abstract:  Spontaneous regression of cancers is extremely rare and is associated with specific malignancies. Spontaneous regression of bronchogenic lung cancer has rarely been reported, and regression of small cell lung cancer is even less common. Such regression is generally ascribed to immunological factors but is not well understood. This case report describes a patient with spontaneous regression of small cell lung cancer that has persisted for 11 years and considers possible mechanisms.

Optically tunable long wavelength infrared quantum cascade laser operated at room temperature

We demonstrate rapid tuning of the emission frequency of a room-temperature mid-infrared quantum cascade laser by external optical pumping. Emission frequency tuning over 0.3 cm−1 (10 GHz) has been achieved for a λ = 9 μm device by optical generation of electron-hole pairs along the entire length of the laser stripe. Measurements indicate that this approach allows for rapid broadband frequency-modulation of mid-infrared quantum cascade lasers at above 300 MHz modulation frequencies.

Z-scan and four-wave mixing characterization of semiconductor cadmium chalcogenide nanomaterials

The possible physical origin of third-order nonlinearity of cadmium chalcogenide (Te, Se, and S) semiconductor nanocrystals were discussed based on the results of both Z-scan and degenerate four-wave mixing spectroscopies at 532, 775, 800, and 1064 nm in nanosecond, picosecond, and femtosecond time scale for nonlinear photonic applications.

Distributed feedback quantum cascade laser with optically tunable emission frequency

Continuous tuning of a room-temperature-operated distributed feedback quantum cascade laser in the range of 0.6 cm−1 (20 GHz) was achieved using 1.3 μm telecom diode laser as a pumping source. We demonstrate wavelength modulation of the quantum cascade laser at frequencies up to 300 MHz.

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.