Dr. David S. Bradshaw Profile

Dr. David S. Bradshaw

Senior Research Associate

SPIE Involvement:

Author

Publications (34)

SPIE Press Book | 1 August 2018

Introduction to Photon Science and Technology

David Andrews, David Bradshaw

KEYWORDS: Polarization, Quantum communications, Photonics, Photon polarization, Absorption, Quantum physics, Particles, Magnetism, Refractive index, Radio propagation

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Introduction to Photon Science and Technology

Proceedings Article | 18 April 2016 Presentation + Paper

Presentation + Paper

On the emergence of Raman signals characterizing multicenter nanoscale interactions

Mathew Williams, David Bradshaw, David Andrews

Proceedings Volume 9884, 98840N (2016) https://doi.org/10.1117/12.2227719

KEYWORDS: Raman spectroscopy, Raman scattering, Nanoparticles, Particles, Quantum electrodynamics, Molecules, Nanophotonics, Scattering, Molecular quantum electrodynamics, Raman spectroscopy, Scattering, Molecular interactions, Chemical analysis, Molecular photonics, Polarization

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Proceedings Article | 4 March 2016 Paper

Paper

Chiral separation and twin-beam photonics

David Bradshaw, David Andrews

Proceedings Volume 9764, 97640W (2016) https://doi.org/10.1117/12.2214926

KEYWORDS: Quantum optics, Singular optics, Nanophotonics, Photonics, Quantum physics, Optical manipulation, Molecules, Molecular interactions, Molecular photonics, Electroluminescence, Photons, Scattering, Particles, Polarizability, Laser scattering, Optical tweezers

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Proceedings Article | 4 March 2016 Paper

Paper

Quantum issues with structured light

Mathew Williams, David Bradshaw, David Andrews

Proceedings Volume 9764, 976407 (2016) https://doi.org/10.1117/12.2214946

KEYWORDS: Quantum optics, Polarization, Quantum physics, Optical vortices, Nanophotonics, Wavefronts, Electromagnetism, Single photon, Singular optics, Spiral phase plates, Structured light, Binary data, Time correlated photon counting, Photon polarization

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Proceedings Article | 31 August 2015 Presentation + Paper

Presentation + Paper

Advanced electrodynamic mechanisms for the nanoscale control of light by light

David Andrews, Jamie Leeder, David Bradshaw

Proceedings Volume 9546, 95460O (2015) https://doi.org/10.1117/12.2190191

KEYWORDS: Laser beam diagnostics, Transistors, Electrodynamics, Nonlinear optics, Photons, Ultrafast phenomena, Scattering, Kerr effect, Light scattering, Chemical species

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Proceedings Article | 25 August 2015 Presentation + Paper

Presentation + Paper

Discriminatory effects in the optical binding of chiral nanoparticles

Kayn Forbes, David Bradshaw, David Andrews

Proceedings Volume 9548, 95480M (2015) https://doi.org/10.1117/12.2188147

KEYWORDS: Particles, Optical binding, Nanoparticles, Optical tweezers, Molecules, Radiation effects, Magnetism, Polarizability, Astatine, Quantum optics

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Proceedings Article | 10 March 2015 Paper

Paper

On the viability of achieving chiral separation through the optical manipulation of molecules

David Andrews, David Bradshaw

Proceedings Volume 9379, 93790Q (2015) https://doi.org/10.1117/12.2076041

KEYWORDS: Molecules, Optical tweezers, Polarization, Magnetism, Molecular lasers, Rayleigh scattering, Liquids, Laser scattering, Scattering, Optical manipulation

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Proceedings Article | 12 September 2014 Paper

Paper

Nanoarrays for the generation of complex optical wave-forms

David Andrews, Mathew Williams, David Bradshaw, Ruifeng Lui, David Phillips, Sonja Franke-Arnold, Miles Padgett

Proceedings Volume 9160, 91601L (2014) https://doi.org/10.1117/12.2060714

KEYWORDS: Spatial light modulators, Spiral phase plates, Wavefronts, Optical vortices, Quantum information, Holography, Excitons, Photodiodes, Holograms, Structured light

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Proceedings Article | 2 May 2014 Paper

Paper

Sculpting optical energy landscapes for multi-particle nanoscale assembly

David Bradshaw, Kayn Forbes, David Andrews

Proceedings Volume 9126, 91260P (2014) https://doi.org/10.1117/12.2051207

KEYWORDS: Particles, Optical binding, Nanoparticles, Spherical lenses, Polarizability, Polarization, Optical tweezers, Quantum electrodynamics, Nanolithography, Atmospheric particles

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Proceedings Article | 2 May 2014 Paper

Paper

Principles of vortex light generation from electronically excited nanoscale arrays

Mathew Williams, David Bradshaw, David Andrews

Proceedings Volume 9126, 91260F (2014) https://doi.org/10.1117/12.2051419

KEYWORDS: Excitons, Optical vortices, Spiral phase plates, Polarization, Optical components, Chromophores, Tin, Dielectric polarization, Computer simulations, Structured light

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Proceedings Article | 1 May 2014 Paper

Paper

Engaging new dimensions in nonlinear optical spectroscopy using auxiliary beams of light

Jack Ford, David Bradshaw, David Andrews

Proceedings Volume 9136, 91361C (2014) https://doi.org/10.1117/12.2051333

KEYWORDS: Absorption, Molecules, Polarization, Molecular interactions, Spectroscopy, Molecular quantum electrodynamics, Optical spectroscopy, Quantum electrodynamics, Nonlinear optics, Photon polarization

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Proceedings Article | 25 February 2014 Paper

Paper

Optical vortex mode generation by nanoarrays with a tailored geometry

Mathew Williams, Matt Coles, David Bradshaw, David Andrews

Proceedings Volume 8999, 89990Q (2014) https://doi.org/10.1117/12.2036772

KEYWORDS: Spiral phase plates, Chromophores, Optical vortices, Excitons, Optical components, Electromagnetism, Electromagnetic radiation, Atmospheric particles, Phase shifts, Structured light

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Proceedings Article | 26 September 2013 Paper

Paper

Expanded horizons for generating and exploring optical angular momentum in vortex structures

David Andrews, Matt Coles, Mathew Williams, David Bradshaw

Proceedings Volume 8813, 88130Y (2013) https://doi.org/10.1117/12.2025141

KEYWORDS: Quantum dots, Polarization, Sensors, Optical vortices, Photon polarization, Excitons, Chemical species, Near field optics, Electronic components, Surface plasmons

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Proceedings Article | 13 September 2013 Paper

Paper

On the detection of characteristic optical emission from electronically coupled nanoemitters

David Bradshaw, Jack Ford, David Andrews

Proceedings Volume 8807, 880703 (2013) https://doi.org/10.1117/12.2022006

KEYWORDS: Sensors, Near field optics, Luminescence, Near field, Signal detection, Excitons, Photodetectors, Radio optics, Neodymium, Electrodynamics

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Proceedings Article | 12 September 2013 Paper

Paper

Near-field manipulation of interparticle forces through resonant absorption, optical binding, and dispersion forces

David Bradshaw, David Andrews

Proceedings Volume 8810, 881025 (2013) https://doi.org/10.1117/12.2022008

KEYWORDS: Optical binding, Absorption, Particles, Photons, Nanoparticles, Dispersion, Near field optics, Near field, Optical tweezers, Molecules

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Proceedings Article | 19 November 2012 Open Access

Open Access

Paper

Controlling the localization and migration of optical excitation

David Andrews, David Bradshaw

Proceedings Volume 8542, 854216 (2012) https://doi.org/10.1117/12.979786

KEYWORDS: Luminescence, Energy transfer, Chromophores, Absorption, Molecular energy transfer, Quantum dots, Spectroscopy, Switching, Transistors, Ultrafast phenomena

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In the nanoscale structure of a wide variety of material systems, a close juxtaposition of optically responsive components can lead to the absorption of light by one species producing fluorescence that is clearly attributable to another. The effect is generally evident in systems comprising two or more light-absorbing components (molecules, chromophores or quantum dots) with well-characterised fluorescence bands at similar, differentiable wavelengths. This enables the fluorescence associated with transferred energy to be discriminated against fluorescence from an initially excited component. The fundamental mechanism at the heart of the phenomenon, molecular (resonance) energy transfer, also operates in systems where the product of optical absorption is optical frequency up-conversion. In contrast to random media, structurally organised materials offer the possibility of pre-configured control over the delocalization of energy, through molecular energy transfer following optical excitation. The Förster mechanism that conveys energy between molecular-scale components is strongly sensitive to specific forms of correlation between the involved components, in terms of position, spectroscopic character, and orientation; one key factor is a spectroscopic gradient. Suitably designed materials offer a broad scope for the widespread exploitation of such features, in applications ranging from chemical and biological sensing to the detection of nanoscale motion or molecular conformations. Recently, attention has turned to the prospect of actively controlling the process of energy migration, for example by changing the relative efficiencies of fluorescence and molecular energy transfer. On application of static electric fields or off-resonant laser light – just two of the possibilities – each represents a means for achieving active control with ultrafast response, in suitably configured systems. As the principles are established and the theory is developed, a range of new possibilities for technical application is emerging. For example, applications can be envisaged for new forms of all-optical switching and transistor action. There is also interest in engaging with the interplay of optical excitation and local nanoscale force, exploiting local responses to changes in dispersion forces, accompanying molecular energy transfer.

Proceedings Article | 22 February 2011 Paper

Paper

Limitations and improvements upon the two-level approximation for molecular nonlinear optics

David Andrews, David Bradshaw, Matt Coles

Proceedings Volume 7917, 79171K (2011) https://doi.org/10.1117/12.873749

KEYWORDS: Nonlinear optics, Systems modeling, Molecules, Frequency conversion, Rayleigh scattering, Molecular quantum electrodynamics, Harmonic generation, Photons, Scattering, Chromophores

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When parametric nonlinear processes are employed in the cause of efficient optical frequency conversion, the media involved are generally subjected to substantially off-resonant input radiation. As such, it is usually only electronic ground states of the conversion material that are significantly populated; higher levels are engaged only in the capacity of virtual states, and it is frequently assumed that just one such state dominates in determining the response. Calculating the nonlinear optical susceptibilities of molecules on this basis, excluding all but the ground and one excited state in a sum-over-states formulation, signifies the adoption of a two-level model, a technique that is widely deployed in the calculation and analysis of nonlinear optical properties. The two-level model offers tractable and physically simple representations of molecular response, including wavelength dependence; it is also the origin of the widely applied 'push-pull' approach to designing optically nonlinear chromophores. By contrast, direct ab initio calculations of optical susceptibility are commonly frustrated by a complete failure to determine such dispersion features. However, caution is required; the two-level model can deliver potentially misleading results if it is applied without regard to the criteria for its validity, especially when molecular excited states are significantly populated. On the basis of a precise, quantum electrodynamical basis for the theory, we explore in detail why there are grounds for questioning the general validity of two-level calculations in nonlinear optics; we assess the criteria for high frequency conversion efficiency and provide a new graphical method to assist in determining the applicability of a two-level model for hyperpolarizability calculations. Lastly, this paper also explores the applicability and detailed conditions for the two-level model for electronically excited molecules, identifying problematic results and providing tractable methods for improving the accuracy of calculations on real molecule-photon interactions.

Proceedings Article | 8 September 2010 Paper

Paper

Optical transistor action by nonlinear coupling of stimulated emission and coherent scattering

David Andrews, David Bradshaw

Proceedings Volume 7797, 77970L (2010) https://doi.org/10.1117/12.862258

KEYWORDS: Transistors, Electronics, Laser scattering, Nonlinear optics, Laser beam diagnostics, Scattering, Complex systems, Telecommunications, Laser damage threshold, Signal processing

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Proceedings Article | 11 May 2010 Paper

Paper

Controlling nanoscale optical emission with off-resonant laser light

David Andrews, Jamie Leeder, David Bradshaw

Proceedings Volume 7712, 77121R (2010) https://doi.org/10.1117/12.854555

KEYWORDS: Luminescence, Quantum dots, Laser beam diagnostics, Nonlinear optics, Absorption, Dispersion, Near field optics, Polarization, Ultrafast phenomena, Atmospheric particles

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Proceedings Article | 25 February 2010 Paper

Paper

Nonlinear optical techniques for improved data capture in fluorescence microscopy and imaging

David Bradshaw, Jamie Leeder, David Andrews

Proceedings Volume 7571, 75710B (2010) https://doi.org/10.1117/12.840946

KEYWORDS: Luminescence, Polarization, Absorption, Photons, Laser beam diagnostics, Multiphoton fluorescence microscopy, Microscopy, Nonlinear optics, Chromophores, Imaging systems

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SPIE Journal Paper | 1 February 2010

Multiple light scattering and optomechanical forces

David Andrews, David Bradshaw, Luciana Davila Romero

JNP, Vol. 4, Issue 01, 041565, (February 2010) https://doi.org/10.1117/12.10.1117/1.3332590

KEYWORDS: Scattering, Raman scattering, Rayleigh scattering, Light scattering, Optical binding, Particles, Optical tweezers, Near field optics, Electromagnetic scattering, Quantum electrodynamics

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SPIE Journal Paper | 1 January 2009

All-optical switching based on controlled energy transfer between nanoparticles in film arrays

David Bradshaw, David Andrews

JNP, Vol. 3, Issue 01, 031503, (January 2009) https://doi.org/10.1117/12.10.1117/1.3079796

KEYWORDS: Switching, Energy transfer, Nanoparticles, Particles, Resolution enhancement technologies, Thin films, Optical switching, Photons, Ultrafast phenomena, Absorption

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Proceedings Article | 10 September 2008 Paper

Paper

All-optical switching based on optical control of energy transfer between thin-film layers

David Bradshaw, David Andrews

Proceedings Volume 7041, 70410K (2008) https://doi.org/10.1117/12.796161

KEYWORDS: Near field optics, Switching, Energy transfer, Nanoparticles, Thin films, Particles, Optical switching, Nonlinear optics, Resolution enhancement technologies, Absorption

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Proceedings Article | 21 August 2008 Paper

Paper

London force and energy transportation between interfacial surfaces

David Bradshaw, Jamie Leeder, Justo Rodríguez, David Andrews

Proceedings Volume 7034, 703408 (2008) https://doi.org/10.1117/12.796083

KEYWORDS: Molecules, Resolution enhancement technologies, Molecular interactions, Dispersion, Interfaces, Molecular quantum electrodynamics, Absorption, Quantum electrodynamics, Spectroscopy, Resonance energy transfer

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Proceedings Article | 23 April 2008 Paper

Paper

The optical control of electronic energy transfer through single and dual auxiliary beams

David Bradshaw, David Andrews

Proceedings Volume 6988, 69880O (2008) https://doi.org/10.1117/12.780248

KEYWORDS: Near field optics, Energy transfer, Particles, Control systems, Resonance energy transfer, Absorption, Atmospheric particles, Resolution enhancement technologies, Switching, Optical switching

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Proceedings Article | 16 April 2008 Paper

Paper

Theory of directed transportation of electronic excitation between single molecules through photonic coupling

D. Andrews, D. Bradshaw

Proceedings Volume 6999, 69990C (2008) https://doi.org/10.1117/12.780573

KEYWORDS: Chromophores, Energy transfer, Near field optics, Molecules, Absorption, Resolution enhancement technologies, Molecular photonics, Resonance energy transfer, Ultrafast phenomena, Near field

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Proceedings Article | 13 February 2008 Paper

Paper

Optical control and switching of excitation transfer in nano-arrays

David Bradshaw, David Andrews

Proceedings Volume 6875, 68750O (2008) https://doi.org/10.1117/12.764448

KEYWORDS: Molecules, Energy transfer, Switching, Near field optics, Resonance energy transfer, Nonlinear optics, Resolution enhancement technologies, Switches, Pulsed laser operation, Electronics

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Proceedings Article | 25 January 2008 Paper

Paper

Resonance energy transfer and interface forces: quantum electrodynamical analysis

David Bradshaw, Jamie Leeder, Justo Rodríguez, David Andrews

Proceedings Volume 6905, 690503 (2008) https://doi.org/10.1117/12.770253

KEYWORDS: Molecules, Resolution enhancement technologies, Particles, Quantum electrodynamics, Geometrical optics, Near field optics, Resonance energy transfer, Interfaces, Solids, Chromophores

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Proceedings Article | 20 April 2006 Paper

Paper

Energy migration in molecular assemblies: the characterisation and differentiation of two-photon mechanisms

David Bradshaw, David Andrews

Proceedings Volume 6195, 61951J (2006) https://doi.org/10.1117/12.662899

KEYWORDS: Absorption, Chromophores, Molecular assembly, Resonance energy transfer, Molecules, Polymers, Dendrimers, Energy transfer, Nanophotonics, Resolution enhancement technologies

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Proceedings Article | 9 February 2006 Paper

Paper

Optical ordering of nanoparticles trapped by Laguerre-Gaussian laser modes

David Bradshaw, David Andrews

Proceedings Volume 6131, 61310G (2006) https://doi.org/10.1117/12.640919

KEYWORDS: Particles, Nanoparticles, Optical tweezers, Modes of laser operation, Laser energy, Quantum electrodynamics, Polarization, Optical vortices, Laser scattering, Atmospheric particles

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Proceedings Article | 19 August 2005 Paper

Paper

Nanoparticle manipulation through inter-particle optical forces and torques

David Bradshaw, David Andrews

Proceedings Volume 5930, 59302A (2005) https://doi.org/10.1117/12.612267

KEYWORDS: Particles, Nanoparticles, Optical tweezers, Quantum electrodynamics, Polarization, Photon polarization, Laser scattering, Optical vortices, Spherical lenses, Scattering

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Proceedings Article | 14 March 2005 Paper

Paper

Optical forces between dielectric nanoparticles in an optical vortex

David Bradshaw, David Andrews

Proceedings Volume 5736, (2005) https://doi.org/10.1117/12.590289

KEYWORDS: Nanoparticles, Dielectrics, Particles, Optical vortices, Quantum electrodynamics, Molecules, Spherical lenses, Molecular quantum electrodynamics, Molecular interactions, Polarizability

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Proceedings Article | 14 October 2004 Paper

Paper

Electronic coupling mechanisms and characteristics for optically nonlinear photoactive nanomaterials

David Andrews, David Bradshaw

Proceedings Volume 5510, (2004) https://doi.org/10.1117/12.555986

KEYWORDS: Nonlinear optics, Resolution enhancement technologies, Absorption, Chromophores, Dendrimers, Photons, Excitons, Resonance energy transfer, Nanomaterials, Energy transfer

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Proceedings Article | 8 September 2004 Paper

Paper

Nonlinear energy pooling in nanophotonic materials

David Andrews, David Bradshaw

Proceedings Volume 5464, (2004) https://doi.org/10.1117/12.544970

KEYWORDS: Chromophores, Resolution enhancement technologies, Nonlinear optics, Dendrimers, Absorption, Nanophotonics, Energy transfer, Excitons, Energy harvesting, Nanomaterials

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Showing 5 of 34 publications

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