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
Demonstration of CW THz generation using a two-color Ti-sapphire laser containing a Fabry-Perot etalon
Describes an experiment demonstrating generation of CW THz radiation from a Ti-sapphire laser. The laser was forced to oscillate on two modes by an intracavity Fabry-Perot etalon. The mode spacing was in the THz range, determined by the etalon thickness. A photoconductive antenna was used as a photomixing element to produce THz radiation, which was then detected by a Golay cell. A simple one-dimen......
#Fabry-Perot #Laser modes #Frequency #Masers #Laser stability #Microchip lasers #Laser noise #Pump lasers #Glass #Distributed Bragg reflectors
An ultra-wide bandwidth photomixer with down conversion at terahertz frequency
We report on the development of an-ultra-broad band photoconductive detector, based on low-temperature-grown GaAs, vertically-integrated with terahertz spiral antennas. Velocity overshoot was expected in the photo-response facing the dramatic decrease in conversion efficiency due to a very short carrier lifetime. Photomixing experiments with two optical 0.8 /spl mu/m laser beating shows a 3-dB ban......
#Bandwidth #Frequency conversion #Optical pumping #Optical frequency conversion #Photoconductivity #Detectors #Gallium arsenide #Spirals #Charge carrier lifetime #Laser modes
Terahertz generation in negative-effective-mass diodes
Theoretically studied current self-oscillations and spatiotemporal current patterns in quantum-well (QW) negative-effective-mass (NEM) p/sup +/pp/sup +/ diodes when the electric field is applied along the direction of the well. The origin of current self-oscillations is the formation and traveling of electric-field domains in the well. In the calculations we have accurately considered scattering c......
#Semiconductor diodes #Phonons #Dispersion #Optical scattering #Spatiotemporal phenomena #Doping #Light scattering #Effective mass #Equations #Steady-state
Multi-channel signal recording with photoconductive antennas for THz imaging
We have constructed a small and cheap, yet efficient electronic circuit for reading out THz signals from photoconductive antennas. An 8-channel version of this circuit has been used for THz imaging by simultaneously recording sets of 8 time-domain THz waveforms with an array of 8 photoconductive antennas.
#Photoconductivity #Pulse amplifiers #Photoconducting devices #Laser excitation #Circuits #Charge coupled devices #Charge-coupled image sensors #Optical pulse generation #Time domain analysis #Antenna arrays
Design and performance of a novel vacuum-capable terahertz time-domain spectrometer
We have designed and built a vacuum-capable terahertz (THz) time-domain spectrometer which allows THz spectroscopy measurements to be made whilst avoiding interference from, for example, water vapour absorption. Using a biased semi-insulating GaAs emitter and a 1-mm-thick [110] oriented ZnTe crystal as an electro-optic detection sensor, we achieved a dynamic range of over 10/sup 10/ in THz power a......
#Time domain analysis #Spectroscopy #Absorption #Zinc compounds #Submillimeter wave measurements #Interference #Gallium arsenide #Electrooptic devices #Dynamic range #Frequency
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
Femtosecond experiments using single-cycle pulses at 30 THz: the buildup of screening in a photoexcited electron-hole plasma
We report on a new class of ultrabroadband THz experiments with a time resolution as high as 30 fs. The measurements rely on single-cycle probe transients which are generated via optical rectification of 10 fs near-infrared pulses in a thin GaSe nonlinear crystal. The electric field of these pulses is directly monitored via ultrabroadband electro-optic detection. On a femtosecond time scale, we ob......
#Plasma displays #Ultrafast optics #Optical scattering #Optical pulses #Plasma measurements #Pulse measurements #Probes #Optical pulse generation #Monitoring #Particle scattering
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