We report on our terahertz study of the reduction effect on graphene oxide films grown on fused silica substrates by spin-coating. The optical characteristics before and after thermal reduction were studied by terahertz time-domain spectroscopy.
We studied the parameters that affect terahertz wave generation via optical rectification in nonlinear crystals. We used simulations based on one-dimensional propagation equations of Maxwell in GaAs to consider the effect of these parameters on conversion efficiency. In order to study the effect of nonlinear absorption, we used Drude-model.
New degrees of freedom in optical design are attained by introducing in the optical path abrupt phase changes over the scale of the wavelength. In this talk, I will discuss experiments on optically thin components based on phase discontinuities and applications
It has been observed that Terahertz (THz) wave was radiation from nanostructured metal gratings and metal films, which was illuminated by femtosecond laser pulse. In this paper, we got more than 60µJ intense single THz pulse, and the maximum spectrum was distributed from 0.3 to 149 THz.
Unusual enhancement of mid-infrared light emission from CdTe/PbTe heterostructures is observed. It is discovered that the observed intense mid-infrared luminescence in the structures comes from the inherent polar interface character and coupling of surface plasmons localized at the metallic CdTe/PbTe interface to light emitted from the narrow gap PbTe.
We have built a 2SB mixer, which has demonstrated a sideband rejection ratio as high as 15 dB over the full band of 600–720 GHz and the SSB noise temperature between 200 and 370 K. Both sideband ration and noise temperature are well within the ALMA specifications.
The propagation of THz waves on a single metallic strip will be presented. The properties and basic applications of this Planar Goubau- Sommerfeld Line (PGSL) will be shown. For example one can realize filters in different ways. The topology of this line is well suited for the excitation of metamaterial's unit cell like split ring resonators (SRR) . We can also take benefit of the propagation on...
Terahertz (THz) light helicity sensitive photoresponse in GaAs/AlGaAs high electron mobility transistors and silicon metal oxide semiconductor field effect transistors is reported. The helicity dependent detection mechanism is interpreted as an interference of plasma oscillations in the channel of the field-effect-transistors (generalized Dyakonov-Shur model). The observed helicity dependent photoresponse...
Millimeter waves as a tool for non- destructive moisture monitoring and disinfestations of artworks are introduced. Non-destructive and non invasive techniques are often irreplaceable in order to preserve and to restore cultural objects. Environmental parameters, first of all moisture, can damage culture heritage objects and also results in spring up variety of pests and other micro-organisms. Non-destructive...
Difference frequency mixing between a resonant bandgap near-infrared beam and a THz wave is demonstrated within the cavity of a quantum cascade laser using a resonantly enhanced second order non-linearity. Conversion efficiencies up to 0.13% are shown that are comparable to those shown by Free Electron Laser measurements.
A new scheme for terahertz modulation based on reconfigurable mesh filters is presented. Compared to existing terahertz modulator solutions, reconfigurable mesh filters have the promise of significant enhancement in modulation index over a broad range of terahertz frequencies.
We report on analysis of military-oriented composite materials by means of THz Time Domain Spectroscopy (TDS) technique in reflection configuration. The composites were hit by a bullet from a rifle and the puncture region was non-destructively imaged. We could observed delaminated and distorted layers inside the sample up to 5mm in depth.
Atacama Large Millimeter Array (ALMA) is an interferometer in Atacama desert in Chile at altitude of 5 km, which is now in a final stage of construction. This array consists of 12-m and 7-m diameter antennas with base line up to 16 km. Each antenna will be equipped with a state of art heterodyne receivers covering atmospheric windows in the range of 30 to 950 GHz. The design of current generation...
Terahertz time domain spectroscopy has been done for reverse micellar solution in the temperature range from ∼190 K to room temperature. The temperature dependence of the absorption lineshape demonstrates that dynamics of water in a nanometer-sized droplet change at low temperatures, which will be ascribed to water shedding from reverse micelles.
We demonstrate the use of broad-band low-intensity terahertz Fourier transform spectroscopy (THz-FTS) for recording the far-infrared (0.1 to 20THz) absorption characteristics of the four nucleobases forming the building blocks of deoxyribonucleic acid (DNA) as well as presenting spectra for various DNA forms. Numerous and distinct spectral features are observed with large differences between the molecules...
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