ORCID Profile
0000-0002-2132-7091
Current Organisation
University of St Andrews
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Publisher: SPIE
Date: 13-09-2012
DOI: 10.1117/12.928494
Publisher: Wiley
Date: 17-09-2013
Publisher: IEEE
Date: 05-2007
Publisher: Wiley
Date: 12-04-2013
Abstract: An organic semiconductor laser, simply fabricated by UV-nanoimprint lithography (UV-NIL), that is pumped with a pulsed InGaN LED is demonstrated. Molecular weight optimization of the polymer gain medium on a nanoimprinted polymer distributed feedback resonator enables the lowest reported UV-NIL laser threshold density of 770 W cm(-2) , establishing the potential for scalable organic laser fabrication compatible with mass-produced LEDs.
Publisher: IEEE
Date: 2005
Publisher: Optica Publishing Group
Date: 2007
DOI: 10.1364/OE.15.003962
Abstract: We report the demonstration of compact fluidic fibre lasers based on capillary tubes and photonic crystal fibres, featuring single channel and multiple laterally integrated fluidic lasers respectively. Their preparation was based on capillary action and lasing occurred without the need for external mirrors or lithographically defined microstructures. The fibre lasers were found to be tunable by varying the chromophore density in the liquid core and a functional wavelength selectivity mechanism inherent in both types of lasers provided a long free spectral range that does not correspond to the length of the fibres. The enhanced mode spacing is attributed to a Vernier resonant effect.
Publisher: IOP Publishing
Date: 22-08-2012
Publisher: AIP Publishing
Date: 22-06-2009
DOI: 10.1063/1.3149827
Abstract: A tunable two-photon pumped solid-state laser based on polyfluorene is reported. A detailed investigation of the two-photon absorption in polyfluorene for both nanosecond and femtosecond time regimes in solution, and solid-state allows the determination of the most favorable conditions for lasing. Tunable distributed feedback lasers are made by spin coating from a polyfluorene solution on corrugated silica substrates and lasing is achieved under two-photon excitation at 640 nm with an absorbed energy density at lasing threshold of 1.3 mJ/cm2. These results highlight an alternative pumping scheme for blue organic semiconductor lasers.
Publisher: Wiley
Date: 19-05-2008
Publisher: Elsevier BV
Date: 07-2010
Publisher: AIP Publishing
Date: 07-2020
DOI: 10.1063/5.0011229
Abstract: Lead halide perovskites are very promising materials for many optoelectronic devices. They are low cost, photostable, and strongly photoluminescent materials, but so far have been little studied for sensing. In this article, we explore hybrid perovskites as sensors for explosive vapor. We tune the dimensionality of perovskite films in order to modify their exciton binding energy and film morphology and explore the effect on sensing response. We find that tuning from the 3D to the 0D regime increases the PL quenching response of perovskite films to the vapor of dinitrotoluene (DNT)—a molecule commonly found in landmines. We find that films of 0D perovskite nanocrystals work as sensitive and stable sensors, with strong PL responses to DNT molecules at concentrations in the parts per billion range. The PL quenching response can easily be reversed, making the sensors reusable. We compare the response to several explosive vapors and find that the response is strongest for DNT. These results show that hybrid perovskites have great potential for vapor sensing applications.
Publisher: IEEE
Date: 06-2007
Publisher: Optica Publishing Group
Date: 2006
DOI: 10.1364/OE.14.009211
Abstract: We report the demonstration of a compact, all-solid-state polymer laser system comprising of a Gallium Nitride (GaN) semiconductor diode laser as the pump source. The polymer laser was configured as a surface emitting, distributed Bragg reflector laser (DBR), based on a novel energy transfer blend of Coumarin 102 and the conjugated polymer poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene). In this configuration, diode pumping was possible both due to the improved quality of the resonators and the improved harvesting of the diode laser light.
Publisher: Wiley
Date: 23-11-2020
Publisher: IEEE
Date: 2005
Publisher: AIP Publishing
Date: 20-08-2007
DOI: 10.1063/1.2761833
Abstract: A study of the lified spontaneous emission (ASE) properties of three bisfluorene-cored dendrimers in the solid state is reported. The results show that the dendron type has a strong impact on the photoluminescence quantum yield and affects the ASE threshold, the optical gain, and loss coefficients. Optically pumped distributed feedback lasers operating in the blue spectral region were fabricated by spin coating the dendrimer films on top of a two-dimensional corrugated fused silica substrate. A best lasing threshold of 4.5μJ∕cm2 and a slope efficiency of 8.3% were obtained, which demonstrate the high potential of these materials for laser applications.
Publisher: IEEE
Date: 06-2007
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: Wiley
Date: 17-06-2021
Abstract: Organic semiconductors possessing tightly bound Frenkel excitons are known to be attractive candidates for demonstrating polariton lasing at room temperature. As polariton lasing can occur without inversion, it is a potential route to very low threshold coherent light sources. However, so far, the thresholds of organic polariton lasers have generally been much higher than those of organic photon lasers. Here this problem has been addressed by investigating two new organic molecules with a structure combining fluorene and carbazole groups. The materials are readily deposited from solution and exhibit high photoluminescence quantum yields, high absorption coefficients, and large radiative decay rates in neat films. Room temperature polariton lasing is realized in both materials with incident thresholds of 13.5 and 9.7 µJ cm −2 , corresponding to absorbed thresholds of 3.3 and 2.2 µJ cm −2 , respectively. These are the lowest values reported to date for polariton lasing in organic semiconductor materials, and approach typical values for organic photon lasers. The step‐like power dependent blue‐shift of polariton modes indicates an interplay between different depletion channels of the exciton reservoir. This work brings practical room temperature polaritonic devices and future realization of electrically driven polariton lasers a step closer.
Publisher: The Optical Society
Date: 10-06-2013
DOI: 10.1364/OE.21.014362
Publisher: SPIE
Date: 18-08-2005
DOI: 10.1117/12.616863
Publisher: Elsevier BV
Date: 11-2021
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Graham Turnbull.