J. E. Cunningham
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Simulated Comparison of On-Chip Terahertz Filters for Sub-Wavelength Dielectric Sensing Open
This paper discusses the application of on-chip terahertz (THz) filters attached to waveguides that can act as sensor elements, including for scanned imaging applications. Our work presents a comparative numerical study of several differen…
View article: Free-space and polarization maintaining delivery of terahertz radiation from a quantum cascade laser in a dry dilution refrigerator
Free-space and polarization maintaining delivery of terahertz radiation from a quantum cascade laser in a dry dilution refrigerator Open
We demonstrate a free-space terahertz (THz) optical system inside a dry dilution refrigerator that allows us to direct polarized THz radiation from a quantum cascade laser (QCL) to a sample held at a base temperature of 28 mK. The sample t…
View article: Asynchronous optical sampling of on-chip terahertz devices for real-time sensing and imaging applications
Asynchronous optical sampling of on-chip terahertz devices for real-time sensing and imaging applications Open
We demonstrate that asynchronous optical sampling (ASOPS) can be used to measure the propagation of terahertz (THz) bandwidth pulses in a coplanar waveguide device with integrated photoconductive switches used for signal excitation and det…
View article: Microscopy of terahertz spoof surface plasmons propagating on planar metamaterial waveguides
Microscopy of terahertz spoof surface plasmons propagating on planar metamaterial waveguides Open
Surface plasmon polaritons (SPPs) are electromagnetic waves that have attracted significant interest owing to their subwavelength confinement and the strong field enhancement that they provide. Yet in the terahertz (THz) frequency region o…
Terahertz microscopy using laser feedback interferometry based on a generalised phase-stepping algorithm Open
In this paper we report an improved method of coherent sensing through the use of a generalized phase-stepping algorithm to extract magnitude and phase information from interferometric fringes acquired by laser feedback interferometry (LFI…
View article: Optical conductivity of a Bi<sub>2</sub>Se<sub>3</sub> topological insulator with a THz transparent top gate
Optical conductivity of a Bi<sub>2</sub>Se<sub>3</sub> topological insulator with a THz transparent top gate Open
We have performed an investigation into the optical conductivity and magnetotransport properties of top-gated devices patterned on the topological insulator Bi 2 Se 3 in order to determine the relative effects of the different carrier spec…
Real-time millimeter wave holography with an arrayed detector Open
Millimeter and terahertz wave imaging has emerged as a powerful tool for applications such as security screening, biomedical imaging, and material analysis. However, intensity images alone are often insufficient for detecting variations in…
Substrate Integrated Bragg Waveguide: an Octave-bandwidth Single-mode Functional Transmission-Line for Millimeter-Wave and Terahertz Applications Open
We demonstrate an air-core single-mode hollow waveguide that uses Bragg reflector structures in place of the vertical metal walls of the standard rectangular waveguide or via holes of the so-called substrate integrated waveguide. The high-…
Enhanced Delivery and Detection of Terahertz Frequency Radiation from a Quantum Cascade Laser Within Dilution Refrigerator Open
We report on significant enhancements to the integration of terahertz (THz) quantum cascade lasers (QCL) and THz detection with a two-dimensional electron gas (2DEG) within a dilution refrigerator obtained by the inclusion of a multi-mesh …
Surface acoustic wave effect on magnetic domain wall dynamics Open
Surface acoustic waves (SAWs) have significant potential for the energy-efficient control of magnetic domain walls (DWs). This study investigates the influence of SAW frequency (50, 100, and 200 MHz) on DW dynamics in magnetic thin films. …
Separation of Heating and Magnetoelastic Coupling Effects in Surface-Acoustic-Wave-Enhanced Creep of Magnetic Domain Walls Open
Surface acoustic waves (SAWs) have significant potential for energy-efficient control of magnetic domain walls (DWs) owing to the magnetoelastic coupling effect. However, the dissipation of radio- frequency (rf) power in a SAW device can r…
Acoustic band engineering in terahertz quantum-cascade lasers and arbitrary superlattices Open
We present theoretical methods for the analysis of acoustic phonon modes in superlattice structures, and terahertz-frequency quantum-cascade lasers (THz QCLs). Our generalized numerical solution of the acoustic-wave equation provides good …
Transport of skyrmions by surface acoustic waves Open
Magnetic skyrmions in thin films with perpendicular magnetic anisotropy are promising candidates for magnetic memory and logic devices, making the development of ways to transport skyrmions efficiently and precisely of significant interest…
View article: The 2023 terahertz science and technology roadmap
The 2023 terahertz science and technology roadmap Open
Terahertz (THz) radiation encompasses a wide spectral range within the electromagnetic spectrum that extends from microwaves to the far infrared (100 GHz–∼30 THz). Within its frequency boundaries exist a broad variety of scientific discipl…
View article: Determination of the Permittivity of Transmission Lines at Milli-Kelvin Temperatures
Determination of the Permittivity of Transmission Lines at Milli-Kelvin Temperatures Open
Many quantum technologies rely heavily on propagation of RF and microwave signals through devices at cryogenic temperatures, and detailed understanding of materials and signal propagation is therefore key to improving the performance of qu…
View article: Efficient free-space to on-chip coupling of THz-bandwidth pulses for biomolecule fingerprint sensing
Efficient free-space to on-chip coupling of THz-bandwidth pulses for biomolecule fingerprint sensing Open
Wide bandwidth THz pulses can be used to record the distinctive spectral fingerprints related to the vibrational or rotational modes of polycrystalline biomolecules, and can be used to resolve the time-dependent dynamics of such systems. W…
Directed delivery of terahertz frequency radiation from quantum cascade lasers within a dry 3He dilution refrigerator Open
We present a scheme for the full integration of terahertz (THz) frequency quantum cascade lasers (QCLs) within a dilution refrigerator in order to provide a directed delivery of THz power into the sample space. We describe a successful ope…
Efficient free-space to chip coupling of ultrafast sub-ps THz pulse for biomolecule fingerprint sensing Open
Ultrafast sub-ps THz pulse conveys rich distinctive spectral fingerprints related to the vibrational or rotational modes of biomolecules and can be used to resolve the time-dependent dynamics of the motions. Thus, an efficient platform for…
Extraction of High-Value Chemicals from Plants for Technical and Medical Applications Open
Plants produce a variety of high-value chemicals (e.g., secondary metabolites) which have a plethora of biological activities, which may be utilised in many facets of industry (e.g., agrisciences, cosmetics, drugs, neutraceuticals, househo…
Design of a Split Ring Resonator Integrated with On‐Chip Terahertz Waveguides for Colon Cancer Detection Open
Finite element method (FEM) simulations (employing ANSYS High Frequency Structure Simulator, HFSS) are used to investigate the response of terahertz (THz) frequency range split‐ring resonators (SRRs) integrated with on‐chip THz waveguides …
View article: Local anisotropy control of Pt/Co/Ir thin film with perpendicular magnetic anisotropy by surface acoustic waves
Local anisotropy control of Pt/Co/Ir thin film with perpendicular magnetic anisotropy by surface acoustic waves Open
The control of perpendicular magnetic anisotropy (PMA) in thin films by strain has considerable potential for energy-efficient information storage and data processing. Here, we report on the control of PMA in Pt/Co/Ir thin films by the str…
View article: Validating S‐parameter measurements of RF integrated circuits at milli‐Kelvin temperatures
Validating S‐parameter measurements of RF integrated circuits at milli‐Kelvin temperatures Open
Techniques to precisely characterise RF components at milli‐Kelvin temperatures support the development of quantum computing systems utilising these components. In this work, an S‐parameter measurement setup to characterise RF integrated c…
Variational Nearest Neighbor Gaussian Process Open
Variational approximations to Gaussian processes (GPs) typically use a small set of inducing points to form a low-rank approximation to the covariance matrix. In this work, we instead exploit a sparse approximation of the precision matrix.…
Enhanced Terahertz Spectral‐Fingerprint Detection of α‐Lactose Using Sub‐Micrometer‐Gap On‐Chip Waveguides Open
We investigate using finite element methods how sub‐micrometer to micrometer‐scale coplanar waveguide (CPW) can be used for the detection of fingerprint spectra of very small (of order 10 −14 mL) volumes of analytes in the terahertz (THz) …
Effect of mesa geometry on low-terahertz frequency range plasmons in two-dimensional electron systems Open
We demonstrate engineering of the low-terahertz range plasmonic spectra of two-dimensional electron systems by modifying their geometry. Specifically, we have modelled, fabricated, and measured two devices for comparison. The first device …
Scattering-induced amplification of two-dimensional plasmons: Electromagnetic modeling Open
Using two rigorous electromagnetic approaches, we study plasmon scattering in two-dimensional systems and show that plasmon amplification is possible in the presence of dc currents. Two scenarios are considered: plasmon scattering from an …
View article: Coherent terahertz microscopy of modal field distributions in micro-resonators
Coherent terahertz microscopy of modal field distributions in micro-resonators Open
Near-field microscopy techniques operating in the terahertz (THz) frequency band offer the tantalizing possibility of visualizing with nanometric resolution the localized THz fields supported by individual resonators, micro-structured surf…
Terahertz magnetoplasmon resonances in coupled cavities formed in a gated two-dimensional electron gas Open
We report on both experiments and theory of low-terahertz frequency range (up to 400 GHz) magnetoplasmons in a gated two-dimensional electron gas at low (<4K) temperatures. The evolution of magnetoplasmon resonances was observed as a funct…
Tunable terahertz band-stop filter using strongly coupled split ring resonators integrated with on-chip waveguide Open
We have used finite-element methods to design and simulate a tunable terahertz frequency range band-stop filter based on coupled split-ring resonators integrated into planar Goubau-line waveguide. Two split-ring resonators with different g…
Dataset associated with "Enhanced Terahertz Spectral-Fingerprint Detection of α-Lactose Using Sub-Micron-Gap On-Chip Waveguides" Open
The results on 'Enhanced Terahertz Spectral-Fingerprint Detection of α-Lactose Using Sub-Micron-Gap On-Chip Waveguides'.