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X Michalet,
R A Colyer,
G Scalia,
A Ingargiola,
R Lin,
J E Millaud,
S Weiss,
Oswald H W Siegmund,
Anton S Tremsin,
John V Vallerga, [......],
D Aharoni,
K Arisaka,
F Villa,
F Guerrieri,
F Panzeri,
I Rech,
A Gulinatti,
F Zappa,
M Ghioni, S Cova
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ABSTRACT: Two optical configurations are commonly used in single-molecule fluorescence microscopy: point-like excitation and detection to study freely diffusing molecules, and wide field illumination and detection to study surface immobilized or slowly diffusing molecules. Both approaches have common features, but also differ in significant aspects. In particular, they use different detectors, which share some requirements but also have major technical differences. Currently, two types of detectors best fulfil the needs of each approach: single-photon-counting avalanche diodes (SPADs) for point-like detection, and electron-multiplying charge-coupled devices (EMCCDs) for wide field detection. However, there is room for improvements in both cases. The first configuration suffers from low throughput owing to the analysis of data from a single location. The second, on the other hand, is limited to relatively low frame rates and loses the benefit of single-photon-counting approaches. During the past few years, new developments in point-like and wide field detectors have started addressing some of these issues. Here, we describe our recent progresses towards increasing the throughput of single-molecule fluorescence spectroscopy in solution using parallel arrays of SPADs. We also discuss our development of large area photon-counting cameras achieving subnanosecond resolution for fluorescence lifetime imaging applications at the single-molecule level.
Philosophical Transactions of The Royal Society B Biological Sciences 01/2013; 368(1611):20120035. · 6.40 Impact Factor
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R. Cubeddu,
A. Bassi,
D. Comelli, S. Cova,
A. Farina,
M. Ghioni,
I. Rech,
A. Pifferi,
L. Spinelli,
P. Taroni,
A. Torricelli,
A. Tosi,
G. Valentini,
F. Zappa
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ABSTRACT: Light is strictly connected with life, and its presence is fundamental for any living environment. Thus, many biological mechanisms are related to light interaction or can be evaluated through processes involving energy exchange with photons. Optics has always been a precious tool to evaluate molecular and cellular mechanisms, but the discovery of lasers opened new pathways of interactions of light with biological matter, pushing an impressive development for both therapeutic and diagnostic applications in biomedicine. The use of light in different fields has become so widespread that the word photonics has been utilized to identify all the applications related to processes where the light is involved. The photonics area covers a wide range of wavelengths spanning from soft X-rays to mid-infrared and includes all devices related to photons as light sources, optical fibers and light guides, detectors, and all the related electronic equipment. The recent use of photons in the field of telecommunications has pushed the technology toward low-cost, compact, and efficient devices, making them available for many other applications, including those related to biology and medicine where these requirements are of particular relevance. Moreover, basic sciences such as physics, chemistry, mathematics, and electronics have recognized the interdisciplinary need of biomedical science and are translating the most advanced researches into these fields. The Politecnico school has pioneered many of them, and this article reviews the state of the art of biomedical research at the Politecnico in the field internationally known as biophotonics.
Pulse, IEEE. 07/2011;
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ABSTRACT: After a brief review of the physics of photon detection in single photon avalanche diode (SPAD) devices, in this paper we will outline the principle of operation of a model we developed with the aim of calculating both photon detection efficiency (PDE) and temporal response (TR) of these detectors. Then we will apply the model to the devices currently available in order to critically analyze some experimental results. We will show in particular how the use of the model allows us to gain a better understanding of the influence of each device parameter in determining both the PDE and the TR. Finally we will discuss some modifications that can be applied to the device structure in order to overcome such limitations. Their effectiveness in improving both the PDE and the TR will be investigated by means of the aforementioned model. The aim is to provide the reader with an insight of which performances can be expected in the next few years if a strong development of the SPAD structure is pursued.
Journal of Modern Optics 02/2011; 58(Nos. 3–4):210-224. · 1.17 Impact Factor
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ABSTRACT: In free-space single-photon quantum key distribution (QKD), the error rate due to daytime background photons can be reduced with strong temporal filtering. In this case, the improvement in performance is determined by the receiver's ability to resolve signal-photon arrival times. We use fast clock recovery and commercially available single-photon detectors with timing resolution enhanced by additional electronic circuitry to implement temporal gating down to 50 ps in a free-space QKD system. The single-photon channel operates at 850 nm, and the improved timing resolution enables transmission rates of 1.25 GHz. We observe daytime quantum bit error rates of 0.04, which is less than one-third of the ungated error rate. We present the design and performance of the system and demonstrate its benefit to free-space QKD.
IEEE Journal of Selected Topics in Quantum Electronics 11/2010; · 3.78 Impact Factor
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ABSTRACT: We present a novel technique for wide dynamic range optical investigations. It is based on a fast-gated silicon single-photon avalanche diode (SPAD) in time-correlated single-photon counting (TCSPC) setup. The SPAD is gated-on and off in 500 ps so as to detect photons only within a given time interval. This technique is particularly useful in applications where a large amount of unnecessary photons precede or follow the optical signal to be detected, such as in time-resolved near infrared (NIR) spectroscopy, optical mammography, and optical molecular imaging. In particular, in time-resolved reflectance spectroscopy, it is desirable to minimize the source-detector separation to improve system performance. This leads to the saturation of the detection electronics because of the huge amount of “early” photons back scattered by superficial layers. Our setup is able to reject these photons and detect only “late” photons from the sample, thus allowing an increase in the dynamic range and the injected power. We acquired diffusive curves of two phantoms with 95 ps time resolution and 10<sup>7</sup> dynamic range with a measurement time three orders of magnitude shorter than what is currently possible with a standard TCPSC setup.
IEEE Journal of Selected Topics in Quantum Electronics 09/2010; · 3.78 Impact Factor
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X Michalet,
R A Colyer,
G Scalia,
T Kim,
Moran Levi,
Daniel Aharoni,
Adrian Cheng,
F Guerrieri,
Katsushi Arisaka,
Jacques Millaud,
I Rech,
D Resnati,
S Marangoni,
A Gulinatti,
M Ghioni,
S Tisa,
F Zappa, S Cova,
S Weiss
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ABSTRACT: Solution-based single-molecule fluorescence spectroscopy is a powerful new experimental approach with applications in all fields of natural sciences. The basic concept of this technique is to excite and collect light from a very small volume (typically femtoliter) and work in a concentration regime resulting in rare burst-like events corresponding to the transit of a single-molecule. Those events are accumulated over time to achieve proper statistical accuracy. Therefore the advantage of extreme sensitivity is somewhat counterbalanced by a very long acquisition time. One way to speed up data acquisition is parallelization. Here we will discuss a general approach to address this issue, using a multispot excitation and detection geometry that can accommodate different types of novel highly-parallel detector arrays. We will illustrate the potential of this approach with fluorescence correlation spectroscopy (FCS) and single-molecule fluorescence measurements obtained with different novel multipixel single-photon counting detectors.
Proceedings - Society of Photo-Optical Instrumentation Engineers 01/2010; 7608(76082D).
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ABSTRACT: Near-Infrared (NIR) picosecond pulsed light shined in biological tissues offers the opportunity for non-invasive imaging.
We aimed at developing a winning photodetector electronics pairing for a broad field of multiple-wavelengths faint-signal
optical investigations, like functional brain imaging. We present an electronic instrumentation based on silicon Single-Photon
Avalanche Diode (SPAD) and fast-gating front-end electronics, in a time-correlated single-photon counting set-up. The high
detection efficiency allows the acquisition of very faint optical signals on a wide spectral range. Furthermore, the fast
gating circuitry enables the detector very quickly (400 ps), thus allowing the rejection of very intense light scattered from
more superficial layers of the head, preceding useful faint signal scattered from the brain. We attain photon-counting dynamic
ranges up to 107 with photon-timing resolutions of 95 ps, thus allowing the detection of photons delayed up to 6 ns from the
laser stimulus.
12/2009: pages 151-154;
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ABSTRACT: InGaAs/InP devices suitable as Single-Photon Avalanche Diodes (SPADs) for photon counting and photon timing applications in
the near-infrared provide good detection efficiency and low time jitter, together with fairly low dark-count rate at moderately
low temperatures. However, their performance is still severely limited by the afterpulsing effect, caused by carriers trapped
into deep levels during the avalanche current flow and later released. We present preliminary experimental characterization
of recently-developed InGaAs/InP detectors that can promisingly be operated slightly cooled. We investigate the primary dark-count
rate, taking into account both thermal generation in the InGaAs absorption layer and trap-assisted tunnelling in the InP multiplication
layer. The fundamental role played by the front-end circuits in minimizing the effects of afterpulsing is assessed and demonstrated.
12/2009: pages 155-159;
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ABSTRACT: Over the past few years there has been a growing interest in monolithic arrays of single photon avalanche diodes (SPAD) for spatially resolved detection of faint ultrafast optical signals. SPADs implemented in CMOS-compatible planar technologies offer the typical advantages of microelectronic devices (small size, ruggedness, low voltage, low power, etc.). Furthermore, they have inherently higher photon detection efficiency than PMTs and are able to provide, beside sensitivities down to single-photons, very high acquisition speeds (i.e. either high frame-rates or very short integration time-slots). In order to make SPAD array more and more competitive in time-resolved application it is necessary to face problems like electrical crosstalk between adjacent pixels.
LEOS Annual Meeting Conference Proceedings, 2009. LEOS '09. IEEE; 11/2009
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ABSTRACT: Recent advances in fluorescence measurements for single molecule spectroscopy, genomics, proteomics and medical diagnostics require single-photon detectors with high quantum efficiency in the extended red spectral range (from 600 nm to 900 nm) and low noise (<50 kc s−1). Amongst industrial production, avalanche photodiodes with large diameter (up to 500 µm) are available which can work in Geiger mode (GM) with good photon detection efficiency (higher than 20%) and some of them also with quite low dark counting rate. They allow one to attain high collection efficiency with simple optical systems. However, they work at high bias voltage (over 200 V) with high power dissipation and are easily damaged by exposure to intense light. A detector carrier module has been designed for safe operation and full performance exploitation of any silicon device suitable for GM operation, with any breakdown voltage up to 480 V. Efficient photon counting and timing is achieved in a very compact module by means of an integrated active-quenching circuit (iAQC) with fast time pickup. Catastrophic failure is avoided by a dedicated monitor and safety circuit, even in the case of exposure to sunlight.
Journal of Modern Optics 01/2009; 56(Nos. 2–3):317-325. · 1.17 Impact Factor
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physica status solidi (a) 04/2008; 18(1):11 - 62. · 1.21 Impact Factor
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ABSTRACT: One of the main drawbacks of single-photon avalanche diode arrays is optical crosstalk between adjacent detectors. In the past, this phenomenon was basically ascribed to light propagating from one detector to another through a direct optical path. Accordingly, deep trenches coated with metal were introduced as optical isolation barriers between pixels. This solution, however, was unable to completely prevent the crosstalk. In this letter, we demonstrate that a strong contribution to optical crosstalk comes from photons reflected at the bottom of the chip. These photons can bypass trenches making them less effective.
IEEE Photonics Technology Letters 04/2008; · 2.19 Impact Factor
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ABSTRACT: The application of quantum key distribution (QKD) has raised particular demands for single-photon detectors. One of the most promising candidates at the low-loss optical fibre communications windows is the planar geometry InGaAs/InP single-photon avalanche diode. These detectors have been modelled, fabricated and characterised at 1.55 mum wavelength. Their performance in terms of single-photon detection efficiency, dark count rate, timing jitter and afterpulsing behaviour are reported and compared with the best commercially available, linear multiplication avalanche photodiodes operated in Geiger-mode. Their use in the application of QKD is discussed.
IET Optoelectronics 01/2008; · 1.03 Impact Factor
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ABSTRACT: We present a new photon timing circuit that achieves a time resolution of 35 ps full width at half maximum with single photon avalanche diodes having active area diameters up to 200 microm. The timing circuit is based on a double avalanche current sensing network that makes it particularly suited to operation at high photon counting rates. Thanks to its self-adjusting capabilities, no trimming is needed even when changing the photodetector operating conditions over a wide range.
Review of Scientific Instruments 09/2007; 78(8):086112. · 1.37 Impact Factor
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ABSTRACT: Silicon single-photon avalanche diodes (SPADs) are nowadays a solid-state alternative to photomultiplier tubes (PMTs) in single-photon counting (SPC) and time-correlated single-photon counting (TCSPC) over the visible spectral range up to 1- mu m wavelength. SPADs implemented in planar technology compatible with CMOS circuits offer typical advantages of microelectronic devices (small size, ruggedness, low voltage, low power, etc.). Furthermore, they have inherently higher photon detection efficiency, since they do not rely on electron emission in vacuum from a photocathode as do PMTs, but instead on the internal photoelectric effect. However, PMTs offer much wider sensitive area, which greatly simplifies the design of optical systems; they also attain remarkable performance at high counting rate, and offer picosecond timing resolution with microchannel plate models. In order to make SPAD detectors more competitive in a broader range of SPC and TCSPC applications, it is necessary to face several issues in the semiconductor device design and technology. Such issues will be discussed in the context of the two possible approaches to such a challenge: employing a standard industrial high-voltage CMOS technology or developing a dedicated CMOS-compatible technology. Advances recently attained in the development of SPAD detectors will be outlined and discussed with reference to both single-element detectors and integrated detector arrays.
IEEE Journal of Selected Topics in Quantum Electronics 08/2007; · 3.78 Impact Factor
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F. Zappa,
S. Tisa, S. Cova,
P. Maccagnani,
R. Saletti,
R. Roncella,
F. Baronti,
D. Bonaccini Calia,
A. Silber,
G. Bonanno,
M. Belluso
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ABSTRACT: A compact system for counting and time-tagging single photons is presented, based on a monolithic array sensor of 60 pixels able to detect single photons, namely the single-photon avalanche diode array (SPADA). First, the working principle and performance of the single-photon detector pixel is detailed, with particular attention paid to monolithic array integration. Then the electronics needed to quench each pixel after avalanche ignition, namely the active-quenching circuit (AQC) is discussed, since the features of this quenching electronics dramatically affect the operating conditions of the detector, hence its actual performance. The discussion then focuses on integration of the SPADA system into Astrophysics applications such as adaptive optics, fast-transient imaging and atmospheric layer sensing. The whole electronics necessary to control SPADA operating conditions and temperature is also described, together with the complete opto-mechanics used to focus the telescope pupil onto the detector. Finally, experimental results are reported.
Journal of Modern Optics 01/2007; 54(Nos. 2–3):163-189. · 1.17 Impact Factor
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ABSTRACT: Single-photon avalanche diodes (SPAD) for 1550 nm wavelength can have InGaAs/InP structure similar to that of avalanche photodiodes of fiber optic systems, but for optimizing the device structure radically different criteria must be adopted. Such criteria are here discussed and a complete experimental characterization of the fabricated device is reported. Remarkable performance is verified also at moderately low temperature, as achieved with Peltier coolers
Solid-State Device Research Conference, 2006. ESSDERC 2006. Proceeding of the 36th European; 10/2006
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ABSTRACT: A new integrated active quenching circuit (i-AQC) designed in a standard CMOS process is presented, capable of operating with any available single photon avalanche diode (SPAD) over wide temperature range. The circuit is suitable for attaining high photon timing resolution also with wide-area SPADs. The new i-AQC integrates the basic active-quenching loop, a patented low-side timing circuit comprising a fast pulse pick-up scheme that substantially improves time-jitter performance, and a novel active-load passive quenching mechanism (consisting of a current mirror rather than a traditional high-value resistor) greatly improves the maximum counting rate. The circuit is also suitable for portable instruments, miniaturized detector modules and SPAD-array detectors. The overall features of the circuit may open the way to new developments in diversified applications of time-correlated photon counting in life sciences and material sciences.
Optics Express 07/2006; 14(12):5021-30. · 3.59 Impact Factor
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ABSTRACT: This paper describes the design, fabrication, and performance of planar-geometry InGaAs-InP devices which were specifically developed for single-photon detection at a wavelength of 1550 nm. General performance issues such as dark count rate, single-photon detection efficiency, afterpulsing, and jitter are described.
IEEE Journal of Quantum Electronics 05/2006; · 1.88 Impact Factor
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ABSTRACT: We have developed a hybrid single photon detection scheme for telecom wavelengths based on nonlinear sum-frequency generation and silicon single-photon avalanche diodes (SPADs). The SPAD devices employed have been designed to have very narrow temporal response, i.e. low jitter ~40 ps, which we can exploit for increasing the allowable bit rate for quantum key distribution. The wavelength conversion is obtained using periodically poled lithium niobate waveguides (W/Gs). The inherently high efficiency of these W/Gs allows us to use a continuous wave laser to seed the nonlinear conversion so as to have a continuous detection scheme. We also present a 1.27 GHz qubit repetition rate, one-way phase encoding, quantum key distribution experiment operating at telecom wavelengths that takes advantage of this detection scheme. The proof-of-principle experiment shows a system capable of MHz raw count rates with a QBER less than 2% and estimated secure key rates greater than 100 kbit s−1 over 25 km.
New Journal of Physics 03/2006; 8(3):32. · 4.18 Impact Factor
