Gerald S. Buller

Heriot-Watt University, Edinburgh, Scotland, United Kingdom

Are you Gerald S. Buller?

Claim your profile

Publications (173)280.16 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper describes progress in gigahertz-clocked quantum key distribution systems. It details current advances in both point-to-point and network applications. We will discuss possibilities for practical quantum key distribution using single-photon sources, and describe a robust gigahertz quantum cryptography system.
    Communications and Photonics Conference and Exhibition (ACP), 2010 Asia; 01/2011
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A 1 x 8 fiber array is used as the front-end of a receiver system. Each channel has a different length of fiber, resulting in each channel signal arriving at the detector at a pre-determined interval relative to a constant repetitive frequency signal. We demonstrate that these eight channels can be efficiently coupled to an individual single-photon detector such that the arrival-time of a photon in each is distinguishable from the next. Thus, we demonstrate spatial position to time information exchange, resulting in a photon-counting array using a single detector. The receiver system could be implemented in numerous applications, including time-resolved photoluminescence, low-light level spectroscopy and quantum information processing.
    Optics Express 01/2011; 19(3):2670-5. DOI:10.1364/OE.19.002670 · 3.53 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Active, three-dimensional long-range imaging using time-correlated single photon counting has the potential for accurate depth resolution at low average power illumination. We report advances in this field.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Single-photon detectors play an increasing role in emerging application areas in quantum communication and low-light level depth imaging. The single-photon detector characteristics have a telling impact in system performance, and this presentation will examine the role of single-photon detectors in these important application areas. We will discuss the experimental system performance of GHz-clocked quantum key distribution systems focusing on issues of quantum bit error rate, net bit rate and transmission distance with different detector structures, concentrating on single-photon avalanche diode detectors, but also examining superconducting nanowire-based structures. The quantum key distribution system is designed to be environmentally robust and an examination of long-term system operation will be presented. The role of detector performance in photon-counting time-of-flight three-dimensional imaging will also be discussed. We will describe an existing experimental test bed system designed for kilometer ranging, and recent experimental results from field trials. The presentation will investigate the key trade-offs in data acquisition time, optical power levels and maximum range. In both examples, experimental demonstrations will be presented to explore future perspectives and design goals.
    Proceedings of SPIE - The International Society for Optical Engineering 01/2011; DOI:10.1117/12.873808 · 0.20 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Using fiber arrays we measure the strength of position and momentum correlations, enabling a full-field demonstration of EPR. We also demonstrate contrast enhancement of images within a ghost-imaging system by use of non-local phase filters.
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper describes progress in gigahertz-clocked quantum key distribution systems. It details current advances in both point-to-point and network applications. We will discuss possibilities for practical quantum key distribution using single-photon sources, and discuss the experimental system performance of GHz-clocked quantum key distribution systems focusing on issues of quantum bit error rate, net bit rate and transmission distance with different detector structures, concentrating on single-photon avalanche diode detectors, but also examining superconducting nanowire-based structures. The quantum key distribution system is designed to be environmentally robust and an examination of long-term system operation will be presented.
    Asia Communications and Photonics Conference and Exhibition; 12/2010
  • [Show abstract] [Hide abstract]
    ABSTRACT: Active, three-dimensional long-range imaging has varied applications in a number of disciplines, including manufacturing, environmental sensing and defence. Common constraints often include low average and peak illumination powers to ensure eye-safety, making the potentially high sensitivity of the single-photon counting technique a distinct advantage. We present a scanning time-of-flight imager based on high repetition-rate (>MHz) pulsed illumination and a silicon single-photon detector. In advanced photon-counting experiments, we recently employed the system for unambiguous range resolution at several kilometres target distance, multiple-surface resolution based on adaptive algorithms, and a cumulative data acquisition method that facilitates detector characterisation and evaluation. This article reviews these achievements and identifies multi-spectral imaging as a possible future application.
    Proceedings of SPIE - The International Society for Optical Engineering 08/2010; DOI:10.1117/12.876144 · 0.20 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A demonstration of the principles of quantum key distribution (QKD) is performed using a single-photon source in a proof of concept test-bed over a distance of 2 km in standard telecommunications optical fiber. The single-photon source was an optically-pumped quantum dot in a microcavity emitting at a wavelength of 895 nm. Characterization of the QKD parameters was performed at a range of different optical excitation powers. An investigation of the effect of varying the optical excitation power of the quantum dot microcavity on the quantum bit error rate and cryptographic key exchange rate of the system are presented.
    Journal of Applied Physics 05/2010; 107(7-107):073102 - 073102-6. DOI:10.1063/1.3327427 · 2.19 Impact Factor
  • Nils J Krichel, Aongus McCarthy, Gerald S Buller
    [Show abstract] [Hide abstract]
    ABSTRACT: Time-correlated single-photon counting techniques have recently been used in ranging and depth imaging systems that are based on time-of-flight measurements. These systems transmit low average power pulsed laser signals and measure the scattered return photons. The use of periodic laser pulses means that absolute ranges can only be measured unambiguously at low repetition rates (typically <100 kHz for > 1 km) to ensure that only one pulse is in transit at any instant. We demonstrate the application of a pseudo-random pattern matching technique to a scanning rangefinder system using GHz base clock rates, permitting the acquisition of unambiguous, three-dimensional images at average pulse rates equivalent to >10 MHz. Depth images with centimeter distance uncertainty at ranges between 50 m and 4.4 km are presented.
    Optics Express 04/2010; 18(9):9192-206. DOI:10.1364/OE.18.009192 · 3.53 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Single-photon detection technologies in conjunction with low laser illumination powers allow for the eye-safe acquisition of time-of-flight range information on non-cooperative target surfaces. We previously presented a photon-counting depth imaging system designed for the rapid acquisition of three-dimensional target models by steering a single scanning pixel across the field angle of interest. To minimise the per-pixel dwelling times required to obtain sufficient photon statistics for accurate distance resolution, periodic illumination at multi- MHz repetition rates was applied. Modern time-correlated single-photon counting (TCSPC) hardware allowed for depth measurements with sub-mm precision. Resolving the absolute target range with a fast periodic signal is only possible at sufficiently short distances: if the round-trip time towards an object is extended beyond the timespan between two trigger pulses, the return signal cannot be assigned to an unambiguous range value. Whereas constructing a precise depth image based on relative results may still be possible, problems emerge for large or unknown pixel-by-pixel separations or in applications with a wide range of possible scene distances. We introduce a technique to avoid range ambiguity effects in time-of-flight depth imaging systems at high average pulse rates. A long pseudo-random bitstream is used to trigger the illuminating laser. A cyclic, fast-Fourier supported analysis algorithm is used to search for the pattern within return photon events. We demonstrate this approach at base clock rates of up to 2 GHz with varying pattern lengths, allowing for unambiguous distances of several kilometers. Scans at long stand-off distances and of scenes with large pixel-to-pixel range differences are presented. Numerical simulations are performed to investigate the relative merits of the technique.
    Proceedings of SPIE - The International Society for Optical Engineering 04/2010; DOI:10.1117/12.850900 · 0.20 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Single-photon sources and detectors are key enabling technologies for photonics in quantum information science and technology (QIST). QIST applications place high-level demands on the performance of sources and detectors; it is therefore essential that their properties can be characterized accurately. Superconducting nanowire single-photon detectors (SNSPDs) have spectral sensitivity from visible to beyond 2 mu m in wavelength, picosecond timing resolution (Jitter < 100 ps FWHM) and the capacity to operate ungated with low dark counts (< 1 kHz). This facilitates data acquisition at high rates with an excellent signal-to-noise ratio. We report on the construction and characterization of a two-channel SNSPD system. The detectors are mounted in a closed-cycle refrigerator, which eliminates reliance on liquid cryogens. Our specification was to deliver a system with 1 % efficiency in both channels at a wavelength of 1310 nm with 1 kHz dark count rate. A full width at half maximum timing jitter of less than 90 ps is achieved in both channels. The system will be used to detect individual photons generated by quantum-optical sources at telecom wavelengths. Examples include single-photon sources based on quantum dots (emitting at 1310 nm). The SNSPD system's spectral sensitivity and timing resolution make it suited to characterization of such sources, and to wider QIST applications.
    Proceedings of SPIE - The International Society for Optical Engineering 04/2010; DOI:10.1117/12.851892 · 0.20 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In recent years, time-correlated single-photon counting techniques have been applied to time-of-flight measurements for long-distance range-finding and depth imaging. Depth imaging has been performed by obtaining timing information from an individual single-photon detector and scanning the optical field to obtain a full depth image. Typically, the measurement is made by dwelling on each individual depth pixel for a pre-defined integration time and completing the data acquisition for that pixel before steering the beam to the adjacent spatial position. We present a novel photon-counting data acquisition mode where the time-of-flight histograms for each depth pixel are gradually populated. The system repeatedly scans the same spatial frame with short per-pixel dwell times, and sufficient photon statistics are built up over many frames by cumulating photon events from all acquired frames. The technique is used to compare the depth imaging performance of two single-photon avalanche diode detectors: a novel, resonant-cavity enhanced shallow-junction device; and a commercially available thick-junction device.
    Journal of Modern Optics 02/2010; 58(3-4-58):244-256. DOI:10.1080/09500340.2010.519445 · 1.17 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: not available.
    Journal of Nanophotonics 01/2010; 4(1). DOI:10.1117/1.3314890 · 1.45 Impact Factor
  • Source
    Robert Lamb, Gerald Buller
    SPIENewsroom 01/2010; DOI:10.1117/2.1201002.002616
  • G. S. Buller, N. J. Krichel, A. McCarthy
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper describes progress on low optical power LIDAR and depth imaging systems using pulsed semiconductor laser diodes and time-correlated single-photon counting.
  • Source
    G. S. Buller, R. J. Collins
    [Show abstract] [Hide abstract]
    ABSTRACT: The detection and generation of single photons has seen an upsurge in interest in recent years as new scientific fields of research, for example quantum information processing, have been established. This review serves to provide an overview of progress in these areas, describing some of the main candidates for single-photon components for use in emerging fields of research.
    Measurement Science and Technology 01/2010; 21(1):12002-28. DOI:10.1088/0957-0233/21/1/012002 · 1.35 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The new generation of 3D imaging systems based on laser radar (ladar) offers significant advantages in defense and security applications. In particular, it is possible to retrieve 3D shape information directly from the scene and separate a target from background or foreground clutter by extracting a narrow depth range from the field of view by range gating, either in the sensor or by postprocessing. We discuss and demonstrate the applicability of full-waveform ladar to produce multilayer 3D imagery, in which each pixel produces a complex temporal response that describes the scene structure. Such complexity caused bymultiple and distributed reflection arises inmany relevant scenarios, for example in viewing partially occluded targets, through semitransparent materials (e.g., windows) and through distributed reflective media such as foliage. We demonstrate our methodology on 3D image data acquired by a scanning time-of-flight system, developed in our own laboratories, which uses the time-correlated single-photon counting technique.
    EURASIP Journal on Advances in Signal Processing 01/2010; 2010:33. DOI:10.1155/2010/896708 · 0.89 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We describe a scanning time-of-flight system which uses the time-correlated single-photon counting technique to produce three-dimensional depth images of distant, noncooperative surfaces when these targets are illuminated by a kHz to MHz repetition rate pulsed laser source. The data for the scene are acquired using a scanning optical system and an individual single-photon detector. Depth images have been successfully acquired with centimeter xyz resolution, in daylight conditions, for low-signature targets in field trials at distances of up to 325 m using an output illumination with an average optical power of less than 50 microW.
    Applied Optics 11/2009; 48(32):6241-51. DOI:10.1364/AO.48.006241 · 1.69 Impact Factor
  • Source
    R.E. Warburton, M.A. Itzler, G.S. Buller
    [Show abstract] [Hide abstract]
    ABSTRACT: Room-temperature operation of InGaAs/InP single-photon avalanche diode detectors operating in free-running mode, with no electrical gating, is demonstrated. An improved design of device structure permitted significantly lower dark count rates than previously reported. Free-running operation at room temperature using an incident wavelength of 1550 nm gave a noise equivalent power of 1.5 10<sup>-15</sup> WHz<sup>-1/2</sup> with improved photon timing jitter.
    Electronics Letters 10/2009; 45(19-45):996 - 997. DOI:10.1049/el.2009.1508 · 1.07 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We describe a scanning time-of-flight system which uses the time-correlated single photon-counting technique to produce three-dimensional depth images of scenes using low average laser power levels (ie < 1 mW). The technique is fundamentally flexible: the trade-off between the integrated number of counts (or acquisition time) against depth resolution permits use in a diverse range of applications. The inherent time gating of the technique, used in conjunction with spatial and spectral filtering, permits operation under high ambient light conditions. Our optical system uses a galvanometer mirror pair to scan the laser excitation over the scene and to direct the collected scattered photon return to an individual silicon single-photon avalanche diode detector. The system uses a picosecond pulsed diode laser at a wavelength of 850nm at MHz repetition rates. The source is directed to the target and the scattered return is collected using a 200mm focal length camera lens. The optical system is housed in a compact custom-designed slotted baseplate optomechanical platform. Currently, the system is capable of a spatial resolution and a depth resolution of better than 10cm at 1km range. We present a series of measurements on a range of non-cooperative target objects.
    Proceedings of SPIE - The International Society for Optical Engineering 05/2009; DOI:10.1117/12.818645 · 0.20 Impact Factor

Publication Stats

2k Citations
280.16 Total Impact Points

Institutions

  • 1989–2015
    • Heriot-Watt University
      • • Institute of Photonics and Quantum Sciences (IPaQS)
      • • School of Engineering and Physical Sciences
      • • Department of Physics
      • • Department of Electrical, Electronic and Computer Engineering
      Edinburgh, Scotland, United Kingdom
  • 2000
    • Politecnico di Milano
      Milano, Lombardy, Italy
  • 1999
    • University of Glasgow
      • Division of Electronics and Electrical Engineering
      Glasgow, Scotland, United Kingdom
  • 1988
    • Edinburgh Instruments, Ltd.
      Edinburgh, Scotland, United Kingdom