Inhee Maeng

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We present terahertz spectroscopic measurements of Dirac fermion dynamics from a large-scale graphene that was grown by chemical vapor deposition and on which carrier density was modulated by electrostatic and chemical doping. The measured frequency-dependent optical sheet conductivity of graphene shows electron-density-dependence characteristics, which can(More)
This paper demonstrates the principle of the nanoparticle-contrast-agent-enabled terahertz imaging (CATHI) technique, which yields a dramatic sensitivity of the differential signal from cancer cells with nanoparticles. The terahertz (THz) reflection signal increased beam by 20% in the cancer cells with nanoparticles of gold nano-rods (GNRs) upon their(More)
We show in this study that nanoparticle composites can be used as contrast agents to enhance the sensitivity of terahertz medical imaging. The terahertz reflection signal increases by nearly 50 % for the sample with nanoparticles upon near infrared laser beam irradiation. This is due to the hyperthermia effect induced by surface plasma polaritons. This(More)
Oscillator-strength sum rule in light-induced transitions is one general form of quantum-mechanical identities. Although this sum rule is well established in equilibrium photo-physics, an experimental corroboration for the validation of the sum rule in a nonequilibrium regime has been a long-standing unexplored question. The simple band structure of(More)
The optical excitation effect on the transmission of a terahertz pulse through aligned silver nanowires on a silicon substrate was studied. Terahertz pulses almost pass through the silver nanowires without optical excitation. However, the optically excited sample significantly reduces the transmittance, comparing with the excited silicon substrate only.
We investigate the relativistic zero balance of the oscillator strength sum rule in a single-layer graphene. The full energy-dependent characteristics are studied by ultrafast THz spectroscopy to probe the low-energy quasi-free absorption oscillator in conjunction with ultrafast optical spectroscopy to investigate the high-energy oscillator near Fermi level.