ORCID Profile
0000-0002-6639-2989
Current Organisation
University Of Strathclyde
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Publisher: AIP Publishing
Date: 16-12-2013
DOI: 10.1063/1.4851875
Abstract: The transfer printing of 2 μm-thick aluminum indium gallium nitride (AlInGaN) micron-size light-emitting diodes with 150 nm (±14 nm) minimum spacing is reported. The thin AlInGaN structures were assembled onto mechanically flexible polyethyleneterephthalate olydimethylsiloxane substrates in a representative 16 × 16 array format using a modified dip-pen nano-patterning system. Devices in the array were positioned using a pre-calculated set of coordinates to demonstrate an automated transfer printing process. In idual printed array elements showed blue emission centered at 486 nm with a forward-directed optical output power up to 80 μW (355 mW/cm2) when operated at a current density of 20 A/cm2.
Publisher: The Optical Society
Date: 13-02-2012
DOI: 10.1364/OME.2.000250
Publisher: AIP Publishing
Date: 04-03-2013
DOI: 10.1063/1.4794078
Abstract: We report modulation bandwidth measurements on a number of InGaN-based quantum well LEDs emitting at 450 and 520 nm wavelengths. It is shown that for these devices the data can be interpreted in terms of Auger recombination, by taking account of the carrier density dependence of the radiative coefficient. We find values for the Auger coefficient of (1±0.3)×10−29cm6s−1 at 450 nm and (3±1)×10−30cm6s−1 at 520 nm.
Publisher: AIP Publishing
Date: 10-2012
DOI: 10.1063/1.4757870
Abstract: Periodically nano-patterned organic films incorporating color converting light-emitting polymers have been integrated onto InGaN/GaN light-emitting diodes (LEDs). Polarized and strongly modified hybrid LED emission is observed due to the photonic crystal effect of the nano-pattern. Emission characteristics are appropriate for various applications, and fast modulation capability with an optical −3 dB bandwidth of 168 MHz is demonstrated.
Publisher: Optica Publishing Group
Date: 08-12-2009
DOI: 10.1364/OE.17.023522
Publisher: The Optical Society
Date: 14-01-2014
DOI: 10.1364/OE.22.001372
Publisher: Springer Science and Business Media LLC
Date: 07-2011
Publisher: The Optical Society
Date: 24-06-2011
DOI: 10.1364/AO.50.003233
Publisher: The Optical Society
Date: 15-03-2013
DOI: 10.1364/OL.38.000992
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 12-2012
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 09-2010
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 06-2009
Publisher: IEEE
Date: 09-2012
Publisher: American Chemical Society (ACS)
Date: 21-05-2018
DOI: 10.1021/ACS.NANOLETT.8B00334
Abstract: Semiconductor nanowire (NW) lasers have attracted considerable research effort given their excellent promise for nanoscale photonic sources. However, NW lasers currently exhibit poor directionality and high threshold gain, issues critically limiting their prospects for on-chip light sources with extremely reduced footprint and efficient power consumption. Here, we propose a new design and experimentally demonstrate a vertically emitting indium phosphide (InP) NW laser structure showing high emission directionality and reduced energy requirements for operation. The structure of the laser combines an InP NW integrated in a cat's eye (CE) antenna. Thanks to the antenna guidance with broken asymmetry, strong focusing ability, and high Q-factor, the designed InP CE-NW lasers exhibit a higher degree of polarization, narrower emission angle, enhanced internal quantum efficiency, and reduced lasing threshold. Hence, this NW laser-antenna system provides a very promising approach toward the achievement of high-performance nanoscale lasers, with excellent prospects for use as highly localized light sources in present and future integrated nanophotonics systems for applications in advanced sensing, high-resolution imaging, and quantum communications.
Publisher: American Chemical Society (ACS)
Date: 04-02-2020
Publisher: IOP Publishing
Date: 03-12-2013
Publisher: Optica Publishing Group
Date: 03-11-2008
DOI: 10.1364/OE.16.018933
Abstract: We report on the integration of monodisperse semiconductor nanocrystal (NC) color converters onto gallium nitride ultraviolet micro-pixelated light-emitting diodes ('micro-LEDs'). Integration is achieved in a 'self-aligned' process by forming a nanocomposite of the respective NCs in a photocurable epoxy polymer. Blue, green, yellow and red NC/epoxy blend microstructures have been successfully integrated onto micro-pixelated LEDs by this technique and utilised for color conversion, resulting in a five color emission single chip. Optical output power density of up to about 166 mW/cm2 is measured spectral emission at 609 nm gives an estimated optical-to-optical conversion as high as 18.2% at 30 mA driving current.
Publisher: IEEE
Date: 10-2011
Publisher: Optica Publishing Group
Date: 2021
DOI: 10.1364/CLEO_SI.2021.STH2F.1
Abstract: In this study, a novel type of broadband polarization-sensitive photoconductive terahertz detectors based on crossed nanowire networks is demonstrated, enabling fast and precise polarization terahertz time-domain spectroscopy measurements.
Publisher: AIP Publishing
Date: 2010
DOI: 10.1063/1.3276156
Abstract: We have systematically investigated the impact of device size scaling on the light output, spectral shift, and self-heating of 400 nm InGaN light-emitting diodes (LEDs). Devices with diameters in the range 20–300 μm have been studied. It is shown that smaller LED pixels can deliver higher power densities (despite the lower absolute output powers) and sustain higher current densities. Investigations of the electroluminescence characteristics of differently sized pixels against current density reveal that the spectral shift is dominated by blueshift at the low current density level and then by redshift at the high current density level, owing to the competition between the bandgap shrinkage caused by self-heating and band-filling effects. The redshift of the emission wavelength with increasing current density is much faster and larger for the bigger pixels, suggesting that the self-heating effect is also size dependent. This is further confirmed by the junction-temperature rise measured by the established spectral shift method. It is shown that the junction-temperature rise in smaller pixels is slower, which in turn explains why the smaller redshift of the emission wavelength with current density is present in smaller pixels. The measured size-dependent junction temperature is in reasonable agreement with finite element method simulation results.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 04-2013
Publisher: Wiley
Date: 17-09-2013
Publisher: SPIE
Date: 30-04-2010
DOI: 10.1117/12.853796
Publisher: Elsevier BV
Date: 11-2010
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2012
Publisher: IEEE
Date: 10-2007
Publisher: American Association for the Advancement of Science (AAAS)
Date: 05-2020
Abstract: Terahertz (THz) radiation is an interesting region of the electromagnetic spectrum lying between microwaves and infrared. Non-ionizing and transparent to most fabrics, it is finding application in security screening and imaging but is also being developed for communication and chemical sensing. To date, most THz detectors have focused just on signal intensity, an effort that discards half the signal in terms of the full optical state, including polarization. Peng et al. developed a THz detector based on crossed nanowires (arranged in a hash structure) that is capable of resolving the full state of the THz light. The approach provides a nanophotonic platform for the further development of THz-based technologies. Science , this issue p. 510
Publisher: IOP Publishing
Date: 29-11-2011
Publisher: The Optical Society
Date: 27-01-2011
DOI: 10.1364/OE.19.002720
Publisher: IOP Publishing
Date: 04-04-2008
Publisher: AIP Publishing
Date: 15-06-2009
DOI: 10.1063/1.3152782
Abstract: A blue-emitting distributed feedback laser based on a star-shaped oligofluorene truxene molecule is presented. The gain, loss, refractive index, and (lack of) anisotropy are measured by lified spontaneous emission and variable-angle ellipsometry. The waveguide losses are very low for an organic semiconductor gain medium, particularly for a neat film. The results suggest that truxenes are promising for reducing loss, a key parameter in the operation of organic semiconductor lasers. Distributed feedback lasers fabricated from solution by spin-coating show a low lasing threshold of 270 W/cm2 and broad tunability across 25 nm in the blue part of the spectrum.
Publisher: Elsevier BV
Date: 2012
Publisher: IOP Publishing
Date: 04-04-2008
Publisher: Optica Publishing Group
Date: 20-06-2008
DOI: 10.1364/OE.16.009918
Abstract: Micropixelated blue (470 nm) and ultraviolet (370 nm) AlInGaN light emitting diode ('micro-LED') arrays have been fabricated in flip-chip format with different pixel diameters (72 microm and 30 microm at, respectively, 100 and 278 pixels/mm(2)). Each micro-LED pixel can be in idually-addressed and the devices possess a specially designed n-common contact incorporated to ensure uniform current injection and consequently uniform light emission across the array. The flip-chip micro-LEDs show, per pixel, high continuous output intensity of up to 0.55 microW/microm(2) (55 W/cm(2)) at an injection current density of 10 kA/cm(2) and can sustain continuous injection current densities of up to 12 kA/cm(2) before breakdown. We also demonstrate that nanosecond pulsed output operation of these devices with per pixel onaxis average peak intensity up to 2.9 microW/microm(2) (corresponding to energy of 45pJ per 22ns optical pulse) can be achieved. We investigate the pertinent performance characteristics of these arrays for micro-projection applications, including the prospect of integrated optical pumping of organic semiconductor lasers.
Publisher: Springer Science and Business Media LLC
Date: 24-04-2009
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 Martin Dawson.