A5058417803- Terahertz technology and applications
- Superconducting and THz Device Technology
- Gyrotron and Vacuum Electronics Research
- Spectroscopy and Laser Applications
- Spectroscopy and Quantum Chemical Studies
- Microwave Engineering and Waveguides
- Photonic and Optical Devices
- Advanced Condensed Matter Physics
- Magnetism in coordination complexes
- Inorganic Fluorides and Related Compounds
- Photonic Crystals and Applications
- Metamaterials and Metasurfaces Applications
- Photorefractive and Nonlinear Optics
- Advanced Antenna and Metasurface Technologies
- Topological Materials and Phenomena
- Mechanical and Optical Resonators
- Semiconductor Quantum Structures and Devices
University of Leeds
2019-2024
We demonstrate a significant enhancement in the sensitivity of split ring resonator terahertz metamaterial dielectric sensors by introduction etched trenches into their inductive-capacitive gap area, both through finite element simulations and experiments performed using time-domain spectroscopy. The enhanced is demonstrated observation an increased frequency shift response to overlaid material thicknesses up 18 µm deposited on sensor surface. show that factor ∼2.7 times incorporation...
Abstract This paper presents a comprehensive study of the optical and electrical dielectric material properties six commonly-used silicon glass substrates at terahertz (THz) frequencies, including refractive index, absorption coefficient, constant loss factor. The characterization techniques used in this feature THz time-domain transmission reflection spectroscopy with measurement frequencies from 0.5 up to maximum 6.5 THz. Of selected semiconductor substrates, two are wafers resistivities...
We report on the design, fabrication and characterisation of large-area photoconductive THz array structures, consisting a thin LT-GaAs active region transferred to an insulating substrate using wafer-scale bonding process. The electrically insulating, transparent reduces parasitic currents in devices, allowing peak THz-fields as high 120 kV cm-1 be generated over bandwidth >5 THz. These results are achieved lower pulse energies than demanded by conventional arrays other popular methods...
We present measurements of the coherence times excited states hydrogen-like arsenic impurities in germanium (Ge:As) using a table-top two-dimensional time-domain spectroscopy (2D-TDS) system. show that this laboratory system is capable resolving lifetimes atomic-like levels impurity centers semiconductors, such as those used solid-state quantum information technologies, on subpicosecond time scale. By fitting coherent nonlinear response with known intracenter transition frequencies, we are...
We report the magnetic structure and properties of a thiocyanate-based honeycomb magnet [Na(OH$_2$)$_3$]Mn(NCS)$_3$ which crystallises in unusual low-symmetry trigonal space group $P\overline{3}$. Magnetic measurements on powder samples show this material is an antiferromagnet (ordering temperature ($T_\mathrm{N,mag} = 18.1(6)\,$)K) can be described by nearest neighbour antiferromagnetic interactions $J=-11.07(4)\,$K. A method for growing neutron-diffraction sized single crystals...
We report the magnetic structure and properties of a thiocyanate-based honeycomb magnet [Na(OH
We report on the development of a large-area photoconductive THz array structure with an LT-GaAs active region fabricated quartz substrates using BCB bonding process. These are shown to generate high THz-fields greater than 100kV/cm, bandwidth 6 THz.
We investigate the effect of effective substrate refractive index on sensitivity terahertz (THz) metamaterials for dielectric sensing by etching. found near can be actively controlled etching, allowing optimization sensitivity. Our experimental findings are in good agreement with finite element method (FEM) simulation results.
An improved electrode geometry is developed for LT-GaAs photoconductive antenna arrays fabricated on transparent sapphire substrates to generate high field THz radiation. These geometries target more efficient generation through supporting biases, higher filling factors and transient photocurrents. Each modification design characterised its effect generation.
High field terahertz spectroscopy measurements of lactose monohydrate are presented. It is found that the feature at 0.53 THz, relating to translatory motion molecules along long axis unit cell, becomes saturated with an incident THz strength 26 kV/cm for a pure powdered sample. We also obtain estimate 1.37 become 205 kV/cm. This nonlinear saturation indicates potential dynamically distorting crystal structure sufficiently high fields.
An improved large area design has been developed for LT-GaAs photoconductive antenna arrays fabricated on optically transparent sapphire substrates to generate high field terahertz (THz) radiation. By optimising a support larger biasing fields, 1.5 times improvement in signal strength resulting fields of up $\sim 200$ kV/cm is reported.
We present broadband nonlinear THz spectroscopy and saturation of hydrogen-like electronic states Arsenic ions, trapped in a solid Geranium substrate. The pulses are generated by photoconductive array.
In this work we discuss the development of a multidimensional terahertz (THz) spectrometer, incorporating range THz generation and detection schemes in order to improve flexibility practicality these complex experimental setups.
Coherence lifetimes (T <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> ) of excited states a hydrogen-like arsenic donor in germanium (Ge:As) have been determined by nonlinear two-dimensional (2D) ultrafast time-domain terahertz spectroscopy at cryogenic temperatures. The derived coherence times for the 2po and $2p\pm$ are 2 ps 0.15 respectively.