ORCID Profile
0000-0001-6117-0896
Current Organisations
Beth Israel Deaconess Medical Center
,
University of Huddersfield
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Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 07-2017
Publisher: The Optical Society
Date: 29-08-2016
DOI: 10.1364/OE.24.020554
Publisher: Oxford University Press (OUP)
Date: 08-1987
DOI: 10.2307/1368635
Publisher: IEEE
Date: 12-2014
Publisher: Optica Publishing Group
Date: 19-10-2009
DOI: 10.1364/OE.17.019926
Publisher: AIP Publishing
Date: 13-08-2007
DOI: 10.1063/1.2770765
Abstract: The effect of GaP strain compensation layers was investigated on ten-layer InGaAs∕GaAs quantum dot infrared photodetectors (QDIPs) grown by metal-organic chemical-vapor deposition. Compared with the normal QDIP structure, the insertion of GaP has led to a narrowed spectral linewidth and slightly improved detector performance. A more significant influence of GaP was observed after the structure was annealed at various temperatures. While a similar amount of wavelength tuning was obtained, the GaP QDIPs exhibited much less degradation in device characteristics with increasing annealing temperature.
Publisher: AIP Publishing
Date: 08-05-2006
DOI: 10.1063/1.2203333
Abstract: We report the experimental results of tuning the emission wavelength of InAs∕InP quantum dots (QDs) by varying either the GaAs interlayer thickness or the indium composition of the InxGa1−xAs interlayer. The InAs QDs are grown on lattice-matched GaInAsP or InP buffers and are capped with an InP layer. As∕P exchange is prominent when the QDs are grown on an InP buffer. A model is developed which considers the As∕P exchange, gallium interdiffusion, strain, and barrier height. Our theoretical and experimental results show that gallium interdiffusion and the As∕P exchange reaction are mainly responsible for the observed shifts in the QD emission wavelength. The model shows that gallium interdiffusion from the interlayer to the InAs QDs grown on a GaInAsP buffer can be utilized to selectively tune the InAs QD emission wavelength over a wide range.
Publisher: IEEE
Date: 10-2011
Publisher: IEEE
Date: 10-2015
Publisher: The Optical Society
Date: 12-09-2013
DOI: 10.1364/OE.21.022194
Publisher: IEEE
Date: 10-2013
Publisher: AIP Publishing
Date: 06-2006
DOI: 10.1063/1.2202704
Abstract: In this work, rapid thermal annealing was performed on InGaAs∕GaAs quantum dot infrared photodetectors (QDIPs) at different temperatures. The photoluminescence showed a blueshifted spectrum in comparison with the as-grown s le when the annealing temperature was higher than 700°C, as a result of thermal interdiffusion of the quantum dots (QDs). Correspondingly, the spectral response from the annealed QDIP exhibited a redshift. At the higher annealing temperature of 800°C, in addition to the largely redshifted photoresponse peak of 7.4μm (compared with the 6.1μm of the as-grown QDIP), a high energy peak at 5.6μm (220meV) was also observed, leading to a broad spectrum linewidth of 40%. This is due to the large interdiffusion effect which could greatly vary the composition of the QDs and thus increase the relative optical absorption intensity at higher energy. The other important detector characteristics such as dark current, peak responsivity, and detectivity were also measured. It was found that the overall device performance was not affected by low annealing temperature, however, for high annealing temperature, some degradation in device detectivity (but not responsivity) was observed. This is a consequence of increased dark current due to defect formation and increased ground state energy.
Publisher: AIP Publishing
Date: 20-04-2015
DOI: 10.1063/1.4918993
Abstract: Terahertz-frequency quantum cascade lasers (THz QCLs) based on bound-to-continuum active regions are difficult to model owing to their large number of quantum states. We present a computationally efficient reduced rate equation (RE) model that reproduces the experimentally observed variation of THz power with respect to drive current and heat-sink temperature. We also present dynamic (time-domain) simulations under a range of drive currents and predict an increase in modulation bandwidth as the current approaches the peak of the light–current curve, as observed experimentally in mid-infrared QCLs. We account for temperature and bias dependence of the carrier lifetimes, gain, and injection efficiency, calculated from a full rate equation model. The temperature dependence of the simulated threshold current, emitted power, and cut-off current are thus all reproduced accurately with only one fitting parameter, the interface roughness, in the full REs. We propose that the model could therefore be used for rapid dynamical simulation of QCL designs.
Publisher: SPIE
Date: 08-12-2016
DOI: 10.1117/12.2250621
Publisher: IEEE
Date: 07-2006
Publisher: American Association for the Advancement of Science (AAAS)
Date: 23-03-2022
DOI: 10.1126/SCITRANSLMED.ABH3831
Abstract: Inflammation has profound but poorly understood effects on metabolism, especially in the context of obesity and nonalcoholic fatty liver disease (NAFLD). Here, we report that hepatic interferon regulatory factor 3 (IRF3) is a direct transcriptional regulator of glucose homeostasis through induction of Ppp2r1b , a component of serine/threonine phosphatase PP2A, and subsequent suppression of glucose production. Global ablation of IRF3 in mice on a high-fat diet protected against both steatosis and dysglycemia, whereas hepatocyte-specific loss of IRF3 affects only dysglycemia. Integration of the IRF3-dependent transcriptome and cistrome in mouse hepatocytes identifies Ppp2r1b as a direct IRF3 target responsible for mediating its metabolic actions on glucose homeostasis. IRF3-mediated induction of Ppp2r1b lified PP2A activity, with subsequent dephosphorylation of AMPKα and AKT. Furthermore, suppression of hepatic Irf3 expression with antisense oligonucleotides reversed obesity-induced insulin resistance and restored glucose homeostasis in obese mice. Obese humans with NAFLD displayed enhanced activation of liver IRF3, with reversion after bariatric surgery. Hepatic PPP2R1B expression correlated with HgbA1C and was elevated in obese humans with impaired fasting glucose. We therefore identify the hepatic IRF3-PPP2R1B axis as a causal link between obesity-induced inflammation and dysglycemia and suggest an approach for limiting the metabolic dysfunction accompanying obesity-associated NAFLD.
Publisher: IEEE
Date: 12-2010
Publisher: AIP Publishing
Date: 22-08-2011
DOI: 10.1063/1.3629991
Abstract: There has been growing interest in the use of terahertz (THz) quantum cascade lasers (QCLs) for sensing applications. However, the lack of compact and sensitive THz detectors has limited the potential for commercial exploitation of sensors based on these devices. We have developed a self-mixing sensing technique in which THz QCLs are used for both generation and interferometric sensing of THz radiation, eliminating the need for a separate detector. Using this technique, we have measured the displacement of a remote target, both with and without opaque (in the visible spectrum) materials in the beam path and demonstrated a stand-off distance of up to 7 m in air.
Publisher: Elsevier BV
Date: 10-2004
Publisher: IEEE
Date: 09-2013
Publisher: IEEE
Date: 07-2016
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 03-2020
Publisher: The Optical Society
Date: 12-09-2016
DOI: 10.1364/OE.24.021948
Publisher: The Optical Society
Date: 07-2011
DOI: 10.1364/OL.36.002587
Publisher: OSA
Date: 2016
Location: United States of America
Location: China
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Paul Harrison.