Proceedings, IEEE Tenth International Conference on Terahertz Electronics
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Self-consistent rate equation modelling of a Terahertz GaAs/AlGaAs quantum-cascade laser
In this work, electron transport in GaAs/AlGaAs quantum cascade lasers operating at far-infrared wavelengths is calculated self-consistently using an intersubband scattering model. Subband populations and carrier transition rates are calculated and all relevant electron-electron and electron-LO phonon scatterings between the injector/collector and active region levels (13-levels in total) are incl......
#Equations #Gallium arsenide #Laser modes #Quantum cascade lasers #Particle scattering #Electrons #Phonons #Laser transitions #Temperature distribution #Threshold current
Terahertz time-domain spectroscopic study of ferroelectrics
A new compact instrument of terahertz time-domain spectrometry (THz-TDS) has been developed to expand the THz-TDS adaptation for far-infrared quantitative measurements on functional materials. THz-TDS enables us to measure simultaneously the spectral amplitude and phase shift in the far-infrared region between 1 and 100 cm/sup -1/ so that the real and imaginary parts of complex dielectric function......
#Time domain analysis #Spectroscopy #Ferroelectric materials #Instruments #Dielectric measurements #Submillimeter wave measurements #Dielectric materials #Phase measurement #Amplitude estimation #Phase estimation
Numerical image enhancement for THz time-domain spectroscopy
Applies numerical image enhancement methods to THz time-domain spectroscopy images in order to improve the quality of experimental data suffering from low resolution and finite focus diameter aperture effects. As an example, the level of detail in a biomedical image of a histopathological sample is shown to increase significantly.
#Image enhancement #Time domain analysis #Spectroscopy #Spatial resolution #Apertures #Image resolution #Biomedical imaging #Visualization #High-resolution imaging #Focusing
Limitations in THz power generation with Schottky diode varactor frequency multipliers
- Trang 109-112
We discuss the limitations in power generation with Schottky diode and HBV (heterostructure barrier varactor) diode frequency multipliers. It is shown that at lower frequencies the experimental results achieved so far approach the theoretical limit of operation for the employed devices. However, at increasing frequencies the power drops with f/sup -3/ instead of the f/sup -2/ predicted by theory. ......
#Power generation #Schottky diodes #Varactors #Frequency #Circuit simulation #Fabrication #Doping #Submillimeter wave devices #Design optimization #Circuit optimization
Integrated THz biomolecular sensors for DNA
A THz wave based approach for the label-free characterization of genetic material is presented. Time-resolved THz spectroscopic analysis of genetic sequences (polynucleotides) demonstrate a clearly distinct complex refractive index in the THz frequency range as a function of the hybridization state (hybridized/denatured) of the analysed DNA sequences. By monitoring THz signals one can thus infer t......
#Biosensors #DNA #Labeling #Fluorescence #Sequences #Frequency #Genetic mutations #Probes #Spectroscopy #Refractive index
Novel concept for THz-photomixer based on periodically doped heterostructures and quasi ballistic transport
Reports on a new concept for THz photomixers, which are not (as usually) frequency limited by the carrier lifetime in low-temperature-grown GaAs. The concept is based on ballistic electron transport in a periodically doped heterostructure (p-i-n-p-i-n-superlattice) and allows for impedance matching to the attached antenna.
#Gallium arsenide #Charge carrier processes #Spontaneous emission #Ballistic transport #Frequency #Charge carrier lifetime #Electron mobility #Space charge #Power lasers #Impedance matching
Detection of terahertz radiation by plasma waves in field effect transistors
We review our recent experimental and theoretical studies of the detection of terahertz radiation in GaAs/AlGaAs heterostructure field effect transistors (FET's) in a wide range of temperatures (8-300 K) and for frequencies ranging from 0.1 THz to 0.6 THz. The resonant detection of 0.6 THz radiation by the two-dimensional electron plasma confined in 0.15 /spl mu/m gate length GaAs/AlGaAs field eff......
#Radiation detectors #Plasma waves #FETs #Gallium arsenide #Plasma temperature #Plasma confinement #HEMTs #MODFETs #Temperature distribution #Frequency
Design considerations for on-chip THz analysis of biomolecules
Recently the marker free distinction between different kinds of biomolecules, e.g. hybridised (double-stranded) DNA (HDNA) and denatured (single-stranded) DNA (DDNA) using THz time-domain on-chip analysis has been demonstrated. Here we numerically examine the influence of critical experimental parameters on the transmission characteristics of a variety of microstrip resonators loaded with test sam......
#Molecular biophysics #DNA #Sequences #Testing #Switches #Fluorescence #Resonance #Refractive index #Microstrip resonators #Genetics
Efficient THz-emitters for low-temperature-grown GaAs photomixers
Different design techniques have been applied to low-temperature grown (LT-) GaAs photomixers and the respective antennas to increase the efficiency and output power of these devices. High DC-photocurrents have been achieved with interdigitated structures and transmission lines have been used to improve matching between antenna and photomixer. The input impedances of antenna structures on GaAs sub......
#Gallium arsenide #Impedance #Fingers #Photoconductivity #Substrates #Conductivity #Voltage #Power transmission lines #Biomembranes #Molecular beam epitaxial growth
Far-infrared spectroscopy of hydrogen bonding in nucleobases, nucleosides, and nucleotides
The far-infrared dielectric properties of organic acids and bases in the condensed phase are dominated by hydrogen bonding between the individual molecules. We have investigated the dielectric properties of nucleobases, nucleosides, and nucleotides. We find that at cold temperatures distinct vibrational modes are present in the frequency range 0.1-4 THz. These modes originate from ordered hydrogen......
#Spectroscopy #Hydrogen #Bonding #DNA #Electromagnetic wave absorption #Pulse shaping methods #Dielectrics #Temperature distribution #Frequency #Molecular biophysics