David Childs
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View article: Towards Fast Quantum Cascade Laser Spectrometers for High-Throughput and Cost-Effective Disease Surveillance
Towards Fast Quantum Cascade Laser Spectrometers for High-Throughput and Cost-Effective Disease Surveillance Open
Fourier transform infrared (FTIR) spectroscopy, coupled with machine learning (ML) analysis can be used for disease monitoring with high speed and accuracy, including the classification of mosquito samples by species, age and malaria detec…
View article: Resonator embedded photonic crystal surface emitting lasers
Resonator embedded photonic crystal surface emitting lasers Open
The finite size of 2D photonic crystals results in them being a lossy resonator, with the normally emitting modes of conventional photonic crystal surface emitting lasers (PCSELs) differing in photon lifetime via their different radiative …
View article: Towards fast quantum cascade laser spectrometers for high-throughput and cost-effective disease surveillance
Towards fast quantum cascade laser spectrometers for high-throughput and cost-effective disease surveillance Open
Fourier transform infrared (FTIR) spectroscopy coupled with Machine Learning (ML) analysis can be used for disease monitoring with high speed and accuracy, including classification of mosquito samples into species and age and malaria detec…
View article: Towards fast quantum cascade laser spectrometers for high-throughput and cost-effective disease surveillance
Towards fast quantum cascade laser spectrometers for high-throughput and cost-effective disease surveillance Open
Fourier transform infrared (FTIR) spectroscopy coupled with Machine Learning (ML) analysis can be used for disease monitoring with high speed and accuracy, including classification of mosquito samples into species and age and malaria detec…
View article: Epitaxially regrown quantum dot photonic crystal surface emitting lasers
Epitaxially regrown quantum dot photonic crystal surface emitting lasers Open
Quantum dot-based epitaxially regrown photonic crystal surface emitting lasers are demonstrated at room temperature. The GaAs-based devices, which are monolithically integrated on the same wafer, exhibit ground state lasing at ∼1230 nm and…
View article: Small signal modulation of photonic crystal surface emitting lasers
Small signal modulation of photonic crystal surface emitting lasers Open
We report the small-signal characterization of a PCSEL device, extracting damping factors and modulation efficiencies, and demonstrating -3 dB modulation bandwidths of up to 4.26 GHz. Based on modelling we show that, by reducing the device…
View article: Extreme temperature operation for broad bandwidth quantum-dot based superluminescent diodes
Extreme temperature operation for broad bandwidth quantum-dot based superluminescent diodes Open
The high-temperature resilience of quantum-dot (QD) laser materials is exploited to realize a broad spectral bandwidth emitter in the near infrared. For an InAs/GaAs-based QD-superluminescent light emitting diode (SLEDs), we introduced a 2…
View article: Polarization-pinning in substrate emission multi-mode vertical-cavity surface-emitting lasers using deep trenches
Polarization-pinning in substrate emission multi-mode vertical-cavity surface-emitting lasers using deep trenches Open
We investigated the stable polarization-pinning properties of substrate emission InGaAs-based 980 nm multi-mode vertical-cavity surface-emitting lasers (VCSELs). For the multi-mode 40 um diameter aperture VCSELs, we introduced 30 μm wide, …
View article: Erratum: “Comparative analysis of void-containing and all-semiconductor 1.5 <i>µ</i>m InP-based photonic crystal surface-emitting laser diodes” [AIP Adv. 11, 065315 (2021)]
Erratum: “Comparative analysis of void-containing and all-semiconductor 1.5 <i>µ</i>m InP-based photonic crystal surface-emitting laser diodes” [AIP Adv. 11, 065315 (2021)] Open
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View article: Micro-PL analysis of high current density resonant tunneling diodes for THz applications
Micro-PL analysis of high current density resonant tunneling diodes for THz applications Open
Low-temperature micro-photoluminescence (μPL) is used to evaluate wafer structural uniformity of current densities >5mA/μm2 InGaAs/AlAs/InP resonant tunneling diode (RTD) structures on different length scales. Thin, highly strained quan…
View article: Micro-photoluminescence characterisation of structural disorder in resonant tunneling diodes for THz applications
Micro-photoluminescence characterisation of structural disorder in resonant tunneling diodes for THz applications Open
We investigated the difference between a macro scale PL and μPL (excitation and detection area ≤ 5μm2). Low-temperature micro-photoluminescence (μPL) is used to evaluate structural perfection of high current density InGaAs/AlAs/InP resonan…
View article: Comparative analysis of void-containing and all-semiconductor 1.5 <i>µ</i>m InP-based photonic crystal surface-emitting laser diodes
Comparative analysis of void-containing and all-semiconductor 1.5 <i>µ</i>m InP-based photonic crystal surface-emitting laser diodes Open
This paper analyzes 2D photonic crystal surface-emitting laser diodes with void-containing and all-semiconductor structures by comparing their simulated mode distribution, band structure, and coupling coefficients. A photonic crystal desig…
View article: Non-diffracting beam generated from a photonic integrated circuit based axicon-like lens
Non-diffracting beam generated from a photonic integrated circuit based axicon-like lens Open
We demonstrate an on-chip silicon-on-insulator (SOI) device to generate a non-diffracting beam of ≈850 µ m length from a diffractive axicon-like lens etched using a low resolution (200 nm feature size, 250 nm gap) deep-ultraviolet lithogra…
View article: Void engineering in epitaxially regrown GaAs-based photonic crystal surface emitting lasers by grating profile design
Void engineering in epitaxially regrown GaAs-based photonic crystal surface emitting lasers by grating profile design Open
We report the engineering of air voids embedded in GaAs-based photonic crystal surface-emitting lasers realized by metalorganic vapor-phase epitaxy regrowth. Two distinct void geometries are obtained by modifying the photonic crystal grati…
View article: Coherent power scaling in photonic crystal surface emitting laser arrays
Coherent power scaling in photonic crystal surface emitting laser arrays Open
A key benefit of photonic crystal surface emitting lasers (PCSELs) is the ability to increase output power through scaling the emission area while maintaining high quality single mode emission, allowing them to close the brightness gap whi…
View article: Power and spectral characterization of photonic integrated circuit based axicon like lens
Power and spectral characterization of photonic integrated circuit based axicon like lens Open
We demonstrate an on-chip Silicon-on-Insulator (SOI) axicon etched using a low resolution (200 nm feature size, 250 nm gap) deep-ultraviolet lithographic fabrication. The axicon consists of circular gratings with seven stages of 1x2 multim…
View article: Resilience of state-of-the-art 1300nm In(Ga)As/GaAs quantum-dot lasers to external optical feedback (Withdrawal Notice)
Resilience of state-of-the-art 1300nm In(Ga)As/GaAs quantum-dot lasers to external optical feedback (Withdrawal Notice) Open
Publisher's Note: This paper was published in error on 1 February 2019 by the publisher and was withdrawn on 15 March 2019. SPIE regrets this error.
View article: Dynamic performance of detuned ridge waveguide AlInGaAs distributed feedback laser diodes
Dynamic performance of detuned ridge waveguide AlInGaAs distributed feedback laser diodes Open
The dynamic behavior of AlInGaAs ridge waveguide distributed feedback lasers is reported in this work covering five detuned wavelengths between 1291 nm and 1326 nm for a laser active layer optical peak gain design centered at 1310 nm at ro…
View article: Gallium nitride light sources for optical coherence tomography
Gallium nitride light sources for optical coherence tomography Open
The advent of optical coherence tomography (OCT) has permitted high-resolution, non-invasive, in vivo imaging of the eye, skin and other biological tissue. The axial resolution is limited by source bandwidth and central wavelength. With th…
View article: Laser diode area melting for high speed additive manufacturing of metallic components
Laser diode area melting for high speed additive manufacturing of metallic components Open
Additive manufacturing processes have been developed to a stage where they can now be routinely used to manufacture net-shape high-value components. Selective Laser Melting (SLM) comprises of either a single or multiple deflected high ener…
View article: Strain balancing of MOVPE InAs/GaAs quantum dots using GaAs 0.8 P 0.2
Strain balancing of MOVPE InAs/GaAs quantum dots using GaAs 0.8 P 0.2 Open
MOVPE growth of stacked InAs/
\nGaAs QDs with and without GaAs
\n0.8
\nP
\n0.2
\n strain balancing layers has been
\nstudied. The GaAsP layers reduce the accumulated strain whilst
\nmaintaining the electrical characteristics. This should…
View article: Mode control in photonic crystal surface emitting lasers through in-plane feedback
Mode control in photonic crystal surface emitting lasers through in-plane feedback Open
Mode control in photonic crystal surface emitting lasers is demonstrated through the use of distributed, varying phase feedback introduced through cleaved facets.
View article: A GaAs-based self-aligned stripe distributed feedback laser
A GaAs-based self-aligned stripe distributed feedback laser Open
We demonstrate operation of a GaAs-based self-aligned stripe (SAS) distributed feedback (DFB) laser. In this structure, a first order GaInP/GaAs index-coupled DFB grating is built within the p-doped AlGaAs layer between the active region a…
View article: GaAs-based self-aligned stripe superluminescent diodes processed normal to the cleaved facet
GaAs-based self-aligned stripe superluminescent diodes processed normal to the cleaved facet Open
We demonstrate GaAs-based superluminescent diodes (SLDs) incorporating a window-like back facet in a self-aligned stripe. SLDs are realised with low spectral modulation depth (SMD) at high power spectral density, without application of ant…
View article: Simulation of broad spectral bandwidth emitters at 1060 nm for optical coherence tomography
Simulation of broad spectral bandwidth emitters at 1060 nm for optical coherence tomography Open
The simulation of broad spectral bandwidth light sources (semiconductor optical amplifiers (SOA) and superluminescent diodes (SLD)) for application in ophthalmic optical coherence tomography is reported. The device requirements and origin …
View article: Three-dimensional finite-difference time-domain modelling of photonic crystal surface-emitting lasers
Three-dimensional finite-difference time-domain modelling of photonic crystal surface-emitting lasers Open
We investigate the beam divergence in far-field region, diffraction loss and optical confinement factors of all-semiconductor and void-semiconductor photonic-crystal surface-emitting lasers (PCSELs), containing either InGaP/GaAs or InGaP/a…
View article: Study of electro-absorption effects in 1300nm In(Ga)As/GaAs quantum dot materials
Study of electro-absorption effects in 1300nm In(Ga)As/GaAs quantum dot materials Open
No abstract available.