Electron transfer is used as a probe for angstrom-scale structural changes in single protein molecules. In flavin reductase, the fluorescence of quenched by nearby tyrosine residue means photo-induced electron transfer. By probing lifetime on photon-by-photon basis, we were able to observe variation flavin-tyrosine distance over time. We could then determine potential mean force between and tyrosine, correlation analysis revealed conformational fluctuation at multiple time scales spanning...

Silicon single-photon avalanche diodes (SPADs) are nowadays a solid-state alternative to photomultiplier tubes (PMTs) in counting (SPC) and time-correlated (TCSPC) over the visible spectral range up 1- <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mu</i> m wavelength. SPADs implemented planar technology compatible with CMOS circuits offer typical advantages of microelectronic devices (small size, ruggedness, low voltage, power, etc.)....

Abstract The evolution of solid-state avalanche detectors single optical photons is outlined and the issues for further progress are discussed. Physical phenomena that underlay operation single-photon diodes (SPAD) determine performance considered their role assessed (detection efficiency; dark-counting rate; afterpulsing; photon timing resolution; etc.). main technological hamper development with wide sensitive area array high filling factor illustrated. Silicon SPADs focus attention;...

We show that quantum frequency conversion (QFC) can overcome the spectral distinguishability common to inhomogeneously broadened solid-state emitters. QFC is implemented by combining single photons from an InAs/GaAs dot (QD) at 980 nm with a 1550 pump laser in periodically poled lithium niobate (PPLN) waveguide generate 600 signal-to-background ratio exceeding $100\ensuremath{\mathbin:}1$. Photon correlation and two-photon interference measurements confirm both photon character wave packet...

An ever wider variety of applications employ Single Photon Avalanche Diodes (SPADs) for the detection faint optical signals. SPADs are p-n junction biased above breakdown voltage and operate in Geiger-mode: each electron-hole pair can trigger an avalanche multiplication process that causes current to swiftly rise its final value. Additional quenching electronics is necessary a SPAD proper working. The additional characteristics directly affect system's obtainable performances. Different...

Physiological monitoring of oxygen delivery to the brain has great significance for improving management patients at risk injury.Diffuse correlation spectroscopy (DCS) is a rapidly growing optical technology able non-invasively assess blood flow index (BFi) bedside.The current limitations DCS are contamination introduced by extracerebral tissue and need know tissue's properties correctly quantify BFi.To overcome these limitations, we have developed new time-resolved diffuse spectroscopy.By...

Abstract Photonic quantum technologies promise a revolution of the world information processing, from simulation and computing to communication sensing, thanks many advantages exploiting single photons as carriers. In this scenario, single‐photon detectors play key role. On one hand, superconducting nanowire (SNSPDs) are able provide remarkable performance on broad spectral range, but their applicability is often limited by need cryogenic operating temperatures. other avalanche diodes...

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 been designed to very narrow temporal response, i.e. low jitter ∼40 ps, which we can exploit increasing the allowable bit rate quantum key distribution. wavelength conversion is obtained using periodically poled lithium niobate waveguides (W/Gs). inherently high efficiency of these W/Gs...

One of the main issues Single Photon Avalanche Diode arrays is optical crosstalk. Since its intensity increases with reducing distance between devices, this phenomenon limits density integration within arrays. In past crosstalk was ascribed essentially to light propagating from one detector another through direct paths. Accordingly, reflecting trenches devices were proposed prevent it, but they proved be not completely effective. paper we will present experimental evidence that a significant...

Abstract In this paper we present a new technology for the fabrication of Single Photon Avalanche Diodes (SPADs) aimed at combining advantages thin and thick SPADs. The detector is manufactured in epitaxial layer designed to improve Detection Efficiency (PDE) red near-infrared range while maintaining good timing resolution. Experimental characterization red-enhanced SPAD (RE-SPAD) confirmed significant improvement PDE compared with SPADs; example wavelength 800 nm has increased from 15%...

It is demonstrated that remarkable timing performance achievable with large area single photon avalanche diodes (SPADs), provided the current sensed at very low level, when multiplication process still confined within a small around absorption point. By employing suitable pick-up circuit, an unprecedented time resolution of 35 ps was obtained 100 µm active diameter SPAD.

We present a novel approach to high-throughput Fluorescence Correlation Spectroscopy (FCS) which enables us obtain one order of magnitude improvement in acquisition time. Our utilizes liquid crystal on silicon spatial light modulator generate dynamically adjustable focal spots, and uses an eight-pixel monolithic single-photon avalanche photodiode array. demonstrate the capabilities this system by showing FCS Rhodamine 6G under various viscosities, that, with proper calibration each detection...

Solution-based single-molecule fluorescence spectroscopy is a powerful experimental tool with applications in cell biology, biochemistry and biophysics. The basic feature of this technique to excite collect light from very small volume work low concentration regime resulting rare burst-like events corresponding the transit single molecule. Detecting photon bursts challenging task: number emitted photons each burst calls for high detector sensitivity. Bursts are brief, requiring detectors...

Substituting noble metals for high-index dielectrics has recently been proposed as an alternative strategy in nanophotonics to design broadband optical resonators and circumvent the ohmic losses of plasmonic materials. In this report, we demonstrate that subwavelength silicon nanoantennas can manipulate photon emission dynamics fluorescent molecules. practice, it is showed dielectric both increase decrease local density states (LDOS) at room temperature, a process inaccessible with...

An improved quantum key distribution test system operating at clock rates of up to 2GHz using a specially adapted commercially-available silicon single-photon counting module is presented. The use an enhanced detector has the fiber-based performance in terms transmission distance and bit error rate.

Recently, a growing interest has arisen about the time-correlated single photon counting (TCSPC) technique, that allows analysis of fast and weak light waveforms with time resolution in picosecond order. Since TCSPC basically consists measurement arrival photon, high linearity block is utmost importance; moreover, use multianode Photo Multiplier Tube avalanche diode arrays led to development multichannel acquisition systems, where be integrated reduce both cost area. We have designed...

Single epitaxially-grown semiconductor quantum dots have great potential as single photon sources for photonic technologies, though in practice devices often exhibit nonideal behavior. Here, we demonstrate that amplitude modulation can improve the performance of quantum-dot-based sources. Starting with a bright source consisting dot fiber-coupled microdisk cavity, use synchronized to temporally filter emitted light. We observe purity, temporal overlap between successive emission events and...

The minimization of the dead time necessary for operation a single-photon avalanche diode (SPAD) plays crucial role in many demanding applications. Among these, it is worth mentioning implementation airborne light detection and ranging systems exploited to scan terrain topography through semiporous obscurations. In this letter, we present development experimental characterization fully integrated active quenching circuit able drive custom-technology SPADs with as low 6.2 ns, corresponding...

Multispectral/hyperspectral fluorescence lifetime imaging microscopy ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>λ</mml:mi> </mml:math> FLIM) is a promising tool for studying functional and structural biological processes. The rich information content provided by multidimensional dataset often in contrast with the acquisition speed. In this work, we develop experimentally demonstrate wide-field FLIM setup, based on novel time-resolved...