1. Richard A. Hogg

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    1. Mentioned In 30 Articles

    2. Near-infrared and mid-infrared semiconductor broadband light emitters

      Near-infrared and mid-infrared semiconductor broadband light emitters
      Semiconductor broadband light emitters have emerged as ideal and vital light sources for a range of biomedical sensing/imaging applications, especially for optical coherence tomography systems. Although near-infrared broadband light emitters have found increasingly wide utilization in these imaging applications, the requirement to simultaneously achieve both a high spectral bandwidth and output power is still challenging for such devices. Owing to the relatively weak amplified spontaneous emission, as a consequence ...
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    3. Growth of quantum three-dimensional structure of InGaAs emitting at ~1 µm applicable for a broadband near-infrared light source

      Growth of quantum three-dimensional structure of InGaAs emitting at ~1 µm applicable for a broadband near-infrared light source
      We obtained a high-intensity and broadband emission centered at ~1 m from InGaAs quantum three-dimensional (3D) structures grown on a GaAs substrate using molecular beam epitaxy. An InGaAs thin layer grown on GaAs with a thickness close to the critical layer thickness is normally affected by strain as a result of the lattice mismatch and introduced misfit dislocations. However, under certain growth conditions for the In concentration and growth temperature ...
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    4. Gallium nitride light sources for optical coherence tomography

      Gallium nitride light sources for optical coherence tomography
      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 the growing demand for short wavelength imaging, super-continuum sources and non-linear fibre-based light sources have been demonstrated in tissue imaging applications exploiting the near-UV and visible spectrum. Whilst the potential has been identified of using gallium ...
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    5. Simulation of broad spectral bandwidth emitters at 1060 nm for retinal optical coherence tomography

      Simulation of broad spectral bandwidth emitters at 1060 nm for retinal optical coherence tomography
      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 of key device parameters are outlined, and a range of single and double InGaAs/GaAs quantum well (QW) active elements are simulated with a view to application in different OCT embodiments. We confirm that utilising higher order optical transitions is ...
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    6. Superluminescent diode with a broadband gain based on self-assembled InAs quantum dots and segmented contacts for an optical coherence tomography light source

      Superluminescent diode with a broadband gain based on self-assembled InAs quantum dots and segmented contacts for an optical coherence tomography light source
      We report a broadband-gain superluminescent diode (SLD) based on self-assembled InAs quantum dots (QDs) for application in a high-resolution optical coherence tomography (OCT) light source. Four InAs QD layers, with sequentially shifted emission wavelengths achieved by varying the thickness of the In 0.2 Ga 0.8 As strain-reducing capping layers, were embedded in a conventional p-n heterojunction comprising GaAs and AlGaAs layers. A ridge-type waveguide with segmented contacts was ...
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    7. GaAs-Based Superluminescent Light-Emitting Diodes with 290-nm Emission Bandwidth by Using Hybrid Quantum Well/Quantum Dot Structures

      GaAs-Based Superluminescent Light-Emitting Diodes with 290-nm Emission Bandwidth by Using Hybrid Quantum Well/Quantum Dot Structures
      A high-performance superluminescent light-emitting diode (SLD) based upon a hybrid quantum well (QW)/quantum dot (QD) active element is reported and is assessed with regard to the resolution obtainable in an optical coherence tomography system. We report on the appearance of strong emission from higher order optical transition from the QW in a hybrid QW/QD structure. This additional emission broadening method contributes significantly to obtaining a 3-dB linewidth of ...
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    8. Lasers and SLEDs for optical coherence tomography

      Lasers and SLEDs for optical coherence tomography
      Optical coherence tomography (OCT) allows for the generation of 3D tomographic images of sub-surface structures in-vivo. This non-destructive, non-ionising process has found application in biological science and clinical diagnosis. Specifically, two versions of the OCT technique have proved optimal for different applications. For retinal imaging through a long length of water, near infrared wavelength super-luminescent diodes (SLEDs) with silicon array detector spectrometer systems have dominated. For imaging turbid media such ...
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    9. Optical characterization of In-flushed InAs/GaAs quantum dots emitting a broadband spectrum with multiple peaks at ~1 μm

      Optical characterization of In-flushed InAs/GaAs quantum dots emitting a broadband spectrum with multiple peaks at ~1 μm
      We investigated optical properties of In-flushed InAs quantum dots (QDs) grown on a GaAs substrate by molecular beam epitaxy. By using the In-flush technique for setting the height of self-assembled InAs QDs, we have tuned the emission wavelength of InAs QDs to the ~1 m regime, which can be utilized as a non-invasive and deeply penetrative probe for biological and medical imaging systems. The controlled emission exhibited a broadband spectrum ...
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    10. Imaging of spectral-domain optical coherence tomography using a superluminescent diode based on InAs quantum dots emitting broadband spectrum with Gaussian-like shape

      Imaging of spectral-domain optical coherence tomography using a superluminescent diode based on InAs quantum dots emitting broadband spectrum with Gaussian-like shape
      We developed a low-coherence light source based on self-assembled InAs quantum dots (QDs) with controlled emission wavelengths and applied it to optical coherence tomography (OCT) imaging. A current-driven superluminescent diode (SLD) light source including four layers of QDs exhibits a broadband (80-nm-bandwidth) emission centered at approximately 1.2 m with a Gaussian-like spectral shape at room temperature. Spectral-domain OCT (SD-OCT) using the QD-SLD as a light source was developed and ...
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    11. Monolithically grown multi-color InAs quantum dots as a spectral-shape-controllable near-infrared broadband light source

      Monolithically grown multi-color InAs quantum dots as a spectral-shape-controllable near-infrared broadband light source
      We have grown monolithic multi-color InAs quantum dots (QDs) for use as a near-infrared (NIR) broadband light source. Our previously developed rotational metal mask enables selective-area growth of QD ensembles with emission peak wavelengths controlled by strain-reducing layers thicknesses, varying the emission approximately 1.21.3 m. The peak shift value was up to 120nm, and a combined 160-nm-bandwidth emission spectrum was achieved. Further, the emission spectra shapes were controlled ...
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    12. Quantum dot selective area intermixing for broadband light sources

      Quantum dot selective area intermixing for broadband light sources
      We report a comparison of different capping materials on the intermixing of modulation p-doped InAs/In(Ga)As quantum dots (QD). QD materials with different caps are shown to exhibit significant difference in their optical properties during the annealing process. The selective area intermixing technique is demonstrated to laterally integrate two and three different QD light emitting devices with a single electrical contact. A spectral bandwidth of 240nm centered at ...
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    13. Self-assembled quantum dot based swept laser source for optical coherence tomography applications

      Self-assembled quantum dot based swept laser source for optical coherence tomography applications
      In this work the use of two identical QD SOAs to enhance the performance of swept laser system for OCT applications is discussed, resulting in an increase in bandwidth up to 94nm. The combination of GaAs based QD SOAs and InP based QW SOAs for realizing broad bandwidth sources for OCT system is described. For the swept laser source a 154nm spectral bandwidth from 1193nm to 1347nm and an average ...
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    14. Optical Coherence Tomography Used $500M of Federally Funded Research Over The Past Decade: How was it Used, What was Accomplished, and What’s to Come?

      Optical Coherence Tomography Used $500M of Federally Funded Research Over The Past Decade: How was it Used, What was Accomplished, and What’s to Come?
      ...F OCT Fund recipients (listed as PIs on the grants) and all have received about $1M in funding.  Ralph Tatam, Richard Hogg, Adrian Podoleanu, Ruikang Wang, Harry Coles, Steve Matcher, Rodney Smallwood, and Haida Liang ar...
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    15. Feature Of The Week 7/3/11: Swept-Source Laser Based on a Quantum Dot Semiconductor Optical Amplifier

      Feature Of The Week 7/3/11: Swept-Source Laser Based on a Quantum Dot Semiconductor Optical Amplifier
      Researchers at the University of Sheffield have been very active in publishing novel results on high performance semiconductors for Optical Coherence Tomography. Recently in collaboration with Innolume they published on a swept-source laser based on a quantum-dot semiconductor optical amplifier. Below is a summary of that work.Swept source lasers (SSL) are a crucial component in Fourier domain optical coherence tomography (OCT) systems. Most SSLs use semiconductor optical amplifiers (SOA ...
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    16. Evaluation of a swept-laser optical coherence tomography light source based on a novel quantum-dot based semiconductor optical amplifier

      Evaluation of a swept-laser optical coherence tomography light source based on a novel quantum-dot based semiconductor optical amplifier
      ...sualized. Nik Krstajic, David Childs, Negin Peyvast, Deepa Kasaragod, Stephen J. Matcher, Igor Krestnikov and Richard Hogg, "Evaluation of a swept-laser optical coherence tomography light source based on a novel quantum-...
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  2. About Richard A. Hogg

    Richard A. Hogg

    Richard Hogg is on the faculty in the Electronic and Electrical Engineering Departement at the University of Sheffield.