A5034860001- Metamaterials and Metasurfaces Applications
- Terahertz technology and applications
- Plasmonic and Surface Plasmon Research
- Superconducting and THz Device Technology
- Photonic and Optical Devices
- Millimeter-Wave Propagation and Modeling
- Advanced Antenna and Metasurface Technologies
- Microwave Engineering and Waveguides
- Advanced Memory and Neural Computing
- Free Radicals and Antioxidants
- Electromagnetic wave absorption materials
- Spectroscopy and Laser Applications
- Insect and Arachnid Ecology and Behavior
- Electrochemical Analysis and Applications
- Neuroscience and Neural Engineering
- Radical Photochemical Reactions
- Gyrotron and Vacuum Electronics Research
- Thermography and Photoacoustic Techniques
- Ferroelectric and Negative Capacitance Devices
- Mechanical and Optical Resonators
- Microwave and Dielectric Measurement Techniques
- Photonic Crystals and Applications
- Topological Materials and Phenomena
Lancaster University
2020-2024
University College London
2024
Metamaterial resonators have become an efficient and versatile platform in the terahertz frequency range, finding applications integrated optical devices, such as active modulators detectors, fundamental research, e.g., ultrastrong light-matter investigations. Despite their growing use, characterization of modes supported by these subwavelength elements has proven to be challenging it still relies on indirect observation collective far-field transmission/reflection properties resonator...
All-electronicultrafast control of terahertz radiation is demonstrated in integrated metamaterial/graphene devices. By electrostatic gating the graphene conductivity, overall optical response incident <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$E$</tex-math></inline-formula> -field modified. Depending on configuration, amplitude, phase, and polarization could be modulated with GHz range reconfiguration...
We report on the terahertz (THz) harmonic generation in an active graphene/metamaterial device by using powerful ultrafast table-top THz time-domain spectroscopic systems. Complex nonlinear transmission spectra, comprising even and odd harmonics, emerge when devices are tested with intense pulses peak electric fields range of 1–150 kV/cm. The features show a positive correlation carrier concentration, allowing for efficient frequency tuning top tunable group delay dispersion. Interestingly,...
Terahertz (THz) near-field imaging and spectroscopy provide valuable insights into the fundamental physical processes occurring in THz resonators metasurfaces on subwavelength scale. However, so far, mapping of surface currents has remained outside scope techniques. In this study, we demonstrate that aperture-type scanning microscopy enables non-contact resonators. Through extensive an asymmetric D-split-ring resonator full electromagnetic simulations probe, correlation between measured...
Synaptic transistors, which emulate the behavior of biological synapses, play a vital role in information processing and storage neuromorphic systems. However, occurrence excessive current spikes during updating synaptic weight poses challenges to stability, accuracy, power consumption transistors. In this work, we experimentally investigate main factors for generation three-terminal transistors that use LiCoO2 (LCO), mixed ionic-electronic conductor, as channel layer. Kelvin probe force...
We report on the ultrafast modulation of a graphene loaded artificial metasurface realized SiO2/Si substrate by near-IR laser pump, detected via terahertz probe at resonant frequency ∼0.8 THz. The results have been acquired setting Fermi energy Dirac point electrostatic gating and illuminating sample with 40 fs pump pulses different fluences, ranging from 0.9 to 0.018 mJ/cm2. sub-ps conductivity rising time was attributed combined effect generation hot carriers in electron–hole silicon. In...
Active modification of the polarization state is a key feature for next-generation wireless communications, sensing, and imaging in THz band. The modulation performance an integrated metamaterial/graphene device investigated via modified time domain spectroscopic system. Graphene’s Fermi level through electrostatic gating, thus modifying device’s overall optical response. tuning ellipticity by <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m1"><mml:mo>></mml:mo></mml:math>...
Terahertz time-domain spectroscopy has experienced significant progress in imaging, spectroscopy, and quality inspection, e.g., for semiconductor packaging or the automotive industry. Additive manufacturing alloys (also known as use 3D printing) have risen popularity aerospace biomedical industries due to ability fabricate intricate designs shapes with high precision using materials customized mechanical properties. However, these 3D-printed elements need be polished thereafter, where...
Abstract Terahertz near-field spectroscopy is a powerful technique for the investigation of metamaterial resonators with subwavelength resolution. Here, we used an a-SNOM THz time domain spectroscopic system direct study all modes supported by individual D-split ring resonators, their E-field distributions and relative Q factors. A cross-polarized excitation detection also demonstrated, yielding modes’ mapping unprecedented resolution sharpness.
We report on the THz harmonic generation in a graphene/metamaterial device by using ultrafast table top powerful THz-TDS systems. A complex nonlinear transmission spectra, which includes peak at third signal is detected of main resonant features 0.65 THz, for E-field pulses range 1-30 kV/cm. Whilst these results are consistent with acquainted literature, they offer novel perspective exploitation graphene nonlinearity integrated devices.
the realization of terahertz external amplitude modulators with a carrier frequency 0.8 THz is presented for application in next generation near-field wireless communications.
Asymmetric split ring resonators supporting high quality factor modes are investigated using aperture near-field microscopy. Modes of varying Q-factor measured, and a novel cross-polarization measurement technique is used to resolve spatial resolution images individual resonators.
Effective control of terahertz radiation requires the development efficient and fast modulators with a large modulation depth. This challenge is often tackled by using metamaterials, artificial sub-wavelength optical structures engineered to resonate at desired frequency. Metamaterial-based devices exploiting graphene as active tuneable element have been proven be highly effective solution for THz modulation. However, whilst conductivity can tuned over wide range, it cannot reduced zero due...
We investigate the modulation performance of a metamaterial/graphene optoelectronic device in THz range. Operating characteristics such as amplitude, phase and polarization modulations broadband radiation are reported. The accomplishments depth include >75% spectral $\gt 15^{\circ}$ phase, 0.2$ active ellipticity ratio, rotational angle changes 20°. These achievements key elements towards efficient manipulations for applications next-generation wireless communications, spectroscopy, imaging.
The ultra-rough surface of the 3D-printed metal produced by laser powder bed fusion technique is one major challenges faced in commercializing metallic components a wider context. electrochemical polishing method currently considered promising to overcome this obstacle. However, evaluating average roughness 3D printed before and after with current state-of-the-art scanning microscopy suffers incomplete datasets due highly scattered signals. Here we successfully evaluate rms surfaces...