1. Articles from r. a. hogg

    1-10 of 10
    1. 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 beneficial for single QW SOAs, but may introduce deleterious spectral modulation in SLDs. We show how an addition QW may be introduced to eliminate this spectral modulation, but that this ...

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    2. 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 1188nm is achieved in a device with two sections. By calculating the point spread function for the obtained emission spectra, and applying the Rayleigh criteria for resolution, an axial resolution ...

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    3. 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 power of 8mW is obtained and for the filtered ASE source a 225 nm bandwidth is demonstrated

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    4. Swept-Source Laser Based on Quantum-Dot Semiconductor Optical Amplifier—Applications in Optical Coherence Tomography

      Swept-Source Laser Based on Quantum-Dot Semiconductor Optical Amplifier—Applications in Optical Coherence Tomography
      We present a swept-source laser based on a quantum-dot semiconductor optical amplifier (QD SOA) (designed and manufactured by Innolume Gmbh, Germany) as the gain medium. The properties of the laser are as follows: center wavelength is 1220 nm, sweep range is 94 nm (up to 120 nm in manual mode), the peak laser power is 16 mW, and the sweep speed is 100 Hz. We apply the laser in an optical coherence tomography (OCT) configuration and present images of in vivo skin. QD SOA are well suited to OCT and we show the setup can be improved for power, sweep ...
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    5. Tuning Superluminescent Diode Characteristics for Optical Coherence Tomography Systems by Utilizing a Multicontact Device Incorporating Wavelength-Modulated Quantum Dots

      This paper details the development of broadband sources at 1050 nm for optical coherence tomography applications. A method for obtaining a broad and smooth emission and gain spectrum for 1050 nm quantum dot (QD) layers is presented. The design, fabrication, and operating characteristics of multicontact superluminescent diodes are then set out, and the operating characteristics of this device, incorporating the broadband QD material, are described. It is shown that this device allows the tuning of the emission spectrum peak position, peak shape, emission bandwidth, and power, which are advantageous for imaging applications. A simplified device, utilizing a single current source ...
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    6. Maximising performance of optical coherence tomography systems using a multi-section chirped quantum dot superluminescent diode

      Key device requirements for maximising resolution in an optical coherence tomography system are discussed. The design and operating parameters of a multi-contact quantum dot superluminescent diode incorporating a number of features which inhibit lasing are described. Such devices allow the independent tuning of emission power and spectral shape; hence the penetration depth and resolution in optical coherence tomography are decoupled. The emission spectrum of a device utilising chirped quantum dots is shown to be tuned to produce a broadband single Gaussian emission, centred at the required wavelength of 1050 nm, with high output powers than a single contact device.
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    7. Multi-section quantum dot superluminescent diodes for spectral shape engineering

      The design and operating parameters of a novel multi-contact quantum dot superluminescent diode incorporating a number of features which inhibit lasing are described and compared with that of a single-contact device. Such devices allow the independent tuning of emission power and spectral shape; hence the penetration depth and resolution in optical coherence tomography are decoupled. The emission spectrum of a device utilising chirped quantum dots is shown to be tuned to produce a broadband single Gaussian emission, centred at the required wavelength of 1050 nm, at higher output powers than a singlecontact device.
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    8. Multi-contact quantum dot superluminescent diodes for optical coherence tomography

      This paper details the development of broadband sources at 1050 nm for optical coherence tomography applications. The careful optimization of the current supplied to different sections of a multi-contact device allows both high power and broadband CW emission to be obtained. ... [Proc. SPIE 7230, 72300C (2009)] published Tue Feb 3, 2009.
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    9. A p-type-doped quantum dot superluminescent LED with broadband and flat-topped emission spectra obtained by post-growth intermixing under a GaAs proximity cap

      A p-type-doped quantum dot superluminescent LED with broadband and flat-topped emission spectra obtained by post-growth intermixing under a GaAs proximity cap
      Broadband superluminescent light emitting diodes are realized by a post-growth annealing process, on modulation p-doped multiple InAs/InGaAs/GaAs quantum dot layer structures, under a GaAs proximity cap. The device exhibits a large and flat emission with spectral width up to 132 nm at 2 mW. This is mainly attributed to the reduction of the energy separation between the ground state and the excited state, in addition to the optical quality of the intermixed modulation p-doped quantum dot materials being comparable to that of the as-grown sample
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    10. Realization of extremely broadband quantum-dot superluminescent light-emitting diodes by rapid thermal-annealing process

      The first demonstration, to our knowledge, of the creation of ultrabroadband superluminescent light-emitting diodes using multiple quantum-dot layer structure by rapid thermal-annealing process is reported. The device exhibits a 3 dB emission bandwidth of 146 nm centered at 984 nm with cw output power as high as 15 mW at room temperature corresponding to an extremely small coherence length of 6.6 μm.
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    1-10 of 10
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  2. Topics in the News

    1. (10 articles) University of Sheffield
    2. (10 articles) Richard A. Hogg
    3. (7 articles) David T. D. Childs
    4. (3 articles) Steven J. Matcher
    5. (3 articles) Nikola Krstajic
    6. (2 articles) Igor Krestnikov
    7. (2 articles) Ziyang Zhang
    8. (2 articles) Alexey Shkolnik
    9. (2 articles) Daniil Livshits
    10. (2 articles) Innolume
    11. (1 articles) Yonsei University
    12. (1 articles) LuEsther T. Mertz Retinal Research Center
    13. (1 articles) Thomas Jefferson University
    14. (1 articles) Università Vita-Salute San Raffaele
    15. (1 articles) University of Coimbra
    16. (1 articles) Florida International University
    17. (1 articles) Ki Hean Kim
    18. (1 articles) Carol L. Shields
    19. (1 articles) K. Bailey Freund
    20. (1 articles) Frank D. Verbraak
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    A p-type-doped quantum dot superluminescent LED with broadband and flat-topped emission spectra obtained by post-growth intermixing under a GaAs proximity cap Swept-Source Laser Based on Quantum-Dot Semiconductor Optical Amplifier—Applications in Optical Coherence Tomography Self-assembled quantum dot based swept laser source for optical coherence tomography applications Quantum dot selective area intermixing for broadband light sources Simulation of broad spectral bandwidth emitters at 1060 nm for retinal optical coherence tomography Human versus Machine: Comparing a Deep Learning Algorithm to Human Gradings for Detecting Glaucoma on Fundus Photographs Absolute linear-in-k spectrometer designs enabled by freeform optics Association of retinal biomarkers and choroidal vascularity index on optical coherence tomography using binarization method in retinitis pigmentosa Skin Imaging using Ultrasound Imaging, Optical Coherence Tomography, Confocal Microscopy, and Two-Photon Microscopy in Cutaneous Oncology Deep learning-based automated detection of retinal diseases using optical coherence tomography images Evaluation of the effects of selective laser trabeculoplasty on anterior segment parameters by anterior segment optical coherence tomography An optical coherence tomography-based grading of diabetic maculopathy proposed by an international expert panel: The European School for Advanced Studies in Ophthalmology classification