A5067770606- Photonic and Optical Devices
- Silicon Carbide Semiconductor Technologies
- Semiconductor Lasers and Optical Devices
- Wood Treatment and Properties
- Semiconductor Quantum Structures and Devices
- Laser-Matter Interactions and Applications
- GaN-based semiconductor devices and materials
- Advancements in Semiconductor Devices and Circuit Design
- HVDC Systems and Fault Protection
- Advanced MEMS and NEMS Technologies
- Advanced Fiber Laser Technologies
- Tree Root and Stability Studies
- Semiconductor materials and devices
- Lignin and Wood Chemistry
- Spectroscopy and Quantum Chemical Studies
- Ga2O3 and related materials
- Wood and Agarwood Research
- Advanced Semiconductor Detectors and Materials
- Advanced Fiber Optic Sensors
- Spectroscopy and Laser Applications
- Advanced Cellulose Research Studies
- Surface Roughness and Optical Measurements
- Cultural Heritage Materials Analysis
- Magnetic Properties and Applications
- Advanced DC-DC Converters
University of Cambridge
2018-2019
Swiss Federal Laboratories for Materials Science and Technology
1990-2016
ABB (Switzerland)
2009-2016
Imperial College London
2013-2014
Auburn University
2014
CEA Paris-Saclay
2014
Institute of Photonic Sciences
2014
Institut Rayonnement-Matière de Saclay
2014
Institució Catalana de Recerca i Estudis Avançats
2014
Spanish Center for Pulsed Lasers
2014
In this paper, we present the development of an air-cooled 1MW bi-directional DC Solid State Circuit Breaker (SSCB) based on recently developed 91mm, 2.5kV Reverse Blocking-IGCT (RB-IGCT). The power electronic switch (RB-IGCT) has been designed and optimized to have very low conduction losses, less than 1kW at 1kA (on-state voltage drop <; 1V 1kA, 400K) high turn-off current capability (> 6.5kA 1.6kV, which are most important concerns semiconductor circuit breaker. We also simulation...
We present theoretical investigations of high-order harmonic generation (HHG) resulting from the interaction noble gases with localized surface plasmons. These plasmonic fields are produced when a metal nanoparticle is subject to few-cycle laser pulse. The enhanced field, which largely depends on geometrical shape metallic structure, has strong spatial dependency. demonstrate that non-homogeneity this field plays an important role in HHG process and leads significant increase cut-off energy....
Activation spectra of wood under natural irradiation were investigated in detail this work. The main purpose was to study colour changes on the surface over time and into depth during light exposure thus further contribute optimization surface-protecting treatments. In a weathering test, three 80-μm-thick strips fir forming layer composite exposed series glass cut-off filters. Samples withdrawn at intervals tested for changes. Identification most detrimental wavebands causing...
This study presents the simulation and experimental results of newly developed 2.5 kV reverse blocking-integrated gate commutated thyristor (RB-IGCT) which has been designed optimised to have very low conduction losses high turn-off current capability for DC solid state circuit breaker (SSCB) applications. The device through anode engineering, thickness resistivity achieve required blocking below 1 kW at kA, that is, on-state voltage drop is as 0.9 V kA. also system level including influence...
In this paper, we review the progress made recently for further developing Integrated Gate Commutated Thyristor (IGCT) device concept high power electronics applications. A wide range of newly introduced IGCT technologies are discussed and recent prototype experimental results as well novel structures future trends technology presented. This will provide system designers with a comprehensive overview potentials possible concept.
Midinfrared vertical external cavity surface emitting lasers for 5μm wavelength have been realized. The active parts consist either of a 2μm thick PbTe gain layer or two 150nm layers embedded in Pb1−xEuxTe barriers, and an epitaxial pair Pb1−yEuyTe∕BaF2 Bragg mirror. They are optically pumped with 1.5μm laser. No precautions efficient heat removal were implemented. two-layer structure emits 1–2mW continuous wave at 95K threshold pump power as low ∼300mW. In pulsed mode, peak powers...
High-efficiency resonant-cavity-enhanced photodetectors for the mid-wavelength infrared range have been realized. Spectral linewidths as narrow 0.07μm at 4.13μm and 0.24μm 8.41μm center wavelength, respectively, achieved. Peak quantum efficiencies are up to above 50%. The photovoltaic devices based on IV-VI semiconductor layers grown epitaxially Si substrates employing a distributed Bragg mirror form cavity.
This paper focuses on the causes that lead to final destruction in standard gate-commutated thyristor (GCT) devices. A new 3-D model approach has been used for simulating GCT which provides a deep insight into operation of extreme conditions. allows drawing some conclusions complex mechanisms drive these devices destruction, previously impossible explain using 2-D models.
We study theoretically photoelectron emission in noble gases using plasmonic enhanced near-fields. demonstrate that these fields have a great potential to generate high energy electrons by direct excitation from mid-infrared laser pulses of current femtosecond oscillators. Typically, appear the surroundings nanostructures with various geometrical shapes, such as bow-ties, metallic waveguides, metal nanoparticles and nanotips, when illuminated short pulse. Here, we consider nanospheres, which...
In this paper, we propose a novel method to extract the accurate junction temperature of an integrated gate commutated thyristor (IGCT) during device conduction (on-state mode), by measuring gate-cathode voltage device. We have shown that is function anode current and T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">vj</sub> . Indeed, can be easily accessed in real-time operation from its gate-unit without need any external power supply or...
We present results on tunable few-cycle laser pulses generated in the near infrared region obtained by filamentation a krypton cell combined with group velocity dispersion compensation fused silica. obtain spectral broadening of factor ∼2–3 over entire domain studied. The central wavelength is tuned from 1.6 μm to 2 via an optical parametric amplification source. In optimum experimental conditions, where input set 1.7 μm, 1.8 and 1.9 incident power gas exceeded critical Krypton ∼4 achieved...
Midinfrared tunable resonant cavity enhanced detectors have been realized. The linewidths of 0.07μm are determined by the finesse cavities, while length can be changed with a movable mirror. This allows tuning across 4–5.5μm midinfrared wavelength range. thin (0.3μm) photodiodes inside based on lead-chalcogenide narrow gap semiconductor layers grown epitaxially onto Si substrate. Due to active layer, higher sensitivity at operation temperatures is achieved as compared conventional thick photodiodes.
Wood is sensitive to photochemical degradation. The development of a wood surface protected against sun radiation remains major challenge. Specimens from different species have been exposed the outdoor environment and analysed at depths time steps by Fourier transform infrared spectroscopy. After 2 months weathering, peak representing C=C aromatic bond disappeared on surface. penetration depth in latewood softwoods less than that earlywood. degradation beech oak more gradual with comparable...