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This paper shows an optical time domain reflectometry (OTDR) system based on an avalanche photodiode (APD) receiver, a 520 nm laser diode transmitter, a high-speed analog-to-digital converter (ADC) and a commercially available field programmable gate array (FPGA). This approach allows OTDR measurements up to 200 m and provides a spatial resolution of 20 cm. Depending on the number of averaging, the measurement time can be between 5 s and 50 s for a range up to 200 m with a good signal to noise ratio. [ABSTRACT FROM AUTHOR]

Photon-counting detector array is very desired for high-resolution laser imaging based on direct time-of-flight measurement. Such systems have potential applications in remote sensing with long distances. We will perform three-dimensional imaging using a large InGaAs Geiger-mode avalanche photodiode array which has single-photon sensitivity. To improve the image quality with only a few photon detections, the photon counting imaging process is analyzed and a regularization method based on pixel spatial correlation is employed for image reconstruction. The performance of the method is compared with that of conventional maximum likelihood estimation on intensity and range image reconstructions of a building about six hundred meters away. [ABSTRACT FROM AUTHOR]

Optical photodetectors are at the forefront of photonic research since the rise of integrated optics. Photodetectors are fundamental building blocks for chip-scale optoelectronics, enabling conversion of light into an electrical signal. Such devices play a key role in many surging applications from communication and computation to sensing, biomedicine and health monitoring, to name a few. However, chip integration of optical photodetectors with improved performances is an on-going challenge for mainstream optical communications at near-infrared wavelengths. Here, we present recent advances in heterostructured silicon-germanium-silicon p-i-n photodetectors, enabling high-speed detection on a foundry-compatible monolithic platform. [ABSTRACT FROM AUTHOR]

Superconducting single-photon detectors (SNSPD) are receivers in optical systems for space communications and exhibit high quantum efficiency and count rate. The receiver in the optical system of atmospheric communication should provide highly efficient detection of radiation with a wavelength of 1.55 μm. The cut-off wavelength of SNSPD is the maximum wavelength of radiation at which high detection efficiency is maintained and depends on the geometrical parameters of the sensitive element of the detector and the thickness and structure of the thin film of superconducting material parameters. In this work, we simulate the cut-off wavelength depending on the thickness of the superconducting film WxSi1-x and the stoichiometric composition with a nanowire width of 100 nm and a ratio of the bias current to the critical 0.7. It is shown that the largest value of the cut-off wavelength λc = 3.06 μm corresponds to a film thickness of 5 nm and a Si content of 25%. With a film thickness of 7 nm, detection with the required wavelength of 1.55 μm is provided over the entire investigated range of the stoichiometric composition of the film: when the Si content is from 15 to 25%. [ABSTRACT FROM AUTHOR]

Mechanical energy (ME) is the sum of potential energy (U) and kinetic energy (K) and associated with the motion and position of an object. The values of ME will always perpetually if the force is constant, while the value of K and U depend on the object position. This study aims to design an apparatus for investigation of the mechanical energy conservation experiment through free fall events using three point photodiode-sensor measurements based on Arduino Uno platform. A prototype is made from PVC cylinder of 100 mm diameter and a height of 100 cm, holed with a height of 100 cm, holed with surface pattern to minimize air friction inside the tube and the acceleration of falling objects is equivalent to the acceleration of the earth's gravity, which is 9.8067 ms-2. Three photodiode sensors are installed straight on the prototype belt to enable the receiver collects light directly from the transmitter while the second sensor is movable up and down to latch the ball travel time, time between interrupts is then measured as well as U and K on an interface. The experiment shows that the decrease in U is proportional to the increase in ME, where the U of objects decreases by 0.0099 Joule every 100 mm distance while K of objects increases by 0.0098 Joule. In the middle of the cylinder with the height of falling objects is 50 cm, then U = K, so the ME value has remained constant. [ABSTRACT FROM AUTHOR]

The NOvA far detector is well suited for finding exotic particles due to its technical features (see [1]). One type of those exotic particles is a "slow" magnetic monopole. It is assumed that the energy deposition of such monopoles should be enough to be registered (see [2]). Measurement of the expected signals was performed on the NOvA test bench at JINR (see [3]). Result of this measurement allows us to perform slow monopole's research using NOvA software and hardware with high efficiency. As a whole, the research can lead to a discovery, or it can limit the existence of monopoles in a wide range of parameters, previously unreachable in other experiments (MACRO, SLIM, RICE, IceCube). Several special software tools have been developed. Slow Monopole Trigger has been created and implemented in the NOvA Data-Driven-Trigger system. Also, an offline reconstruction algorithm has been developed and tested on 5% of the data. A technical description of these tools and current results of the analysis are presented in this work. [ABSTRACT FROM AUTHOR]

A lidar receiver with a direct detection chain adapted to a HgCdTe APD based detector with electric cooling is associated to a 2.05 μm Ho :YLF pulsed dual wavelength single mode transmitter to provide the first atmospheric lidar measurements using this technology. Experiments confirm the outstanding sensitivity of the detector and hightligth its huge potential for DIAL measurements of trace gas (CO2 and H2O) in this spectral domain. Performances of coherent vs direct detection at 2.05 μm is assessed. [ABSTRACT FROM AUTHOR]

In this work we report on design and testing of an HgCdTe Avalanche Photodiode (APD) detector assembly for lidar applications in the Short Wavelength Infrared Region (SWIR : 1,5 - 2 μm). This detector consists in a set of diodes set in parallel -making a 200 μm large sensitive area- and connected to a custom high gain TransImpedance Amplifier (TIA). A commercial four stages Peltier cooler is used to reach an operating temperature of 185K. Crucial performances for lidar use are investigated : linearity, dynamic range, spatial homogeneity, noise and resistance to intense illumination. [ABSTRACT FROM AUTHOR]

We developed a silicon avalanche photodiode (Si-APD) linear-array detector to be used for time-resolved X-ray scattering experiments using synchrotron X-rays. The Si-APD linear array consists of 64 pixels (pixel size: 100 × 200 μm²) with a pixel pitch of 150 μm and a depletion depth of 10 μm. The multichannel scaler counted X-ray pulses over continuous 2046 time bins for every 0.5 ns and recorded a time spectrum at each pixel with a time resolution of 0.5 ns (FWHM) for 8.0 keV X-rays. Using the detector system, we were able to observe X-ray peaks clearly separated with 2 ns interval in the multibunch-mode operation of the Photon Factory ring. The small-angle X-ray scattering for polyvinylidene fluoride film was also observed with the detector. [ABSTRACT FROM AUTHOR]

We developed a scintillation X-ray detector using a proportional-mode silicon avalanche photodiode (Si-APD). We report a prototype detector using a lead-loaded plastic scintillator mounted on a proportional-mode Si-APD (active area size: 3 mm in diameter), which is operated at a low temperature. Using 67.41 keV X-rays, we could measure pulse-height spectra of scintillation light with a charge-sensitive preamplifier at 20, 0, and -35°C. Time spectra of the X-ray bunch structure were successfully recorded using a wideband and 60-dB-gain amplifier in hybrid-mode operation of the Photon Factory ring. We obtained a better time resolution of 0.51 ns (full width at half-maximum) for the single-bunch X-ray peak at -35°C. We were also able to observe a linear response of the scintillation pulses up to 8 Mcps for input photon rates up to 1.4 × 108 photons/s. [ABSTRACT FROM AUTHOR]

In the paper we analyze factors reducing the possible accuracy of the heterodyne laser interferometers. The analysis is performed for the avalanche-photodiode input stages but is in main points valid also for stages with other type of photodetectors. Instrumental error originating from optical, electronic and digital signal processing factors is taken into consideration. We stress factors which are critical and those which can be neglected at certain accuracy requirements. In the work we prove that it is possible to reduce errors of the laser instrument below 1 nm point for multiaxial APD based interferometers by precise control of incident optical power and the temperature of the photodiode. [ABSTRACT FROM AUTHOR]

Avalanche Photodiode based on InGaAs/InP was chosen because of the needs of high speed optical receivers and have their own advantages on high sensitivity. In this project, we focused on the effect of guard ring on InGaAs/InP avalanche photodiodes and its performance. Three types of guard ring structures are designed in APD and their current-voltage (I-V) characteristics (electric field profiles) are simulated and analyzed. In this paper, the characteristics of guard ring in InGaAs/InP are investigated using Silvaco software, TCAD tools. This paper investigates the effects of guardring (GR) structures on the performance of InGaAs/InP avalanche photodiode (APDs) designed in Silvaco TCAD. Three type InGaAs/InP-APDs based on P+/N-well guard ring , n+/p-substrate guard ring and no presence guard ring are designed and their electric field profiles are simulated. In others to know the best structures of InGaAs/InP avalanche photodiode structures, the current-voltage characteristics (I-V characteristics) are measured and compared. Overall, the project includes the effect and relationship of avalanche photodiode between substrate concentrations and doping, type of materials, with the breakdown voltage and leakage current were investigated. Then, the structure is applied with guard ring structure. At the end, we choose the best optimized design of avalanche photodiode based on current-voltage characteristics. From the theoretical, they conclude the important of guard ring presence in the avalanche photodiode structure in order to avoid premature breakdown and also leakage current. From the experiment, we can conclude that the best structures of InGaAs/InP avalanche photodiode is by using P+/N-well guard ring because this structure give the higher breakdown voltage and lowest leakage current. [ABSTRACT FROM AUTHOR]

We report a normal incidence Ge/Si avalanche photodiode with separate-absorption-charge-multiplication (SACM) structure by selective epitaxial growth. By proper design of charge and multiplication layers and by optimizing the electric field distribution in the depletion region to eliminate germanium impact-ionization at high gain, a high gain-bandwidth product of 310 GHz has been achieved at 1550 nm. [ABSTRACT FROM PUBLISHER]

A high-resolution hold-off time control circuit for Geiger-mode avalanche photodiodes (GM-APDs) that enables linear changes to the hold-off time from several nanoseconds to microseconds is presented. The resolution of the hold-off time can be varied from nanoseconds to tens of nanoseconds with a range up to 1.2 µs to cater for a variety of GM-APDs. This circuit allows setting of the optimal ‘afterpulse-free’ hold-off time for any GM-APD through digital inputs or additional signal processing circuitry. The layout area is 95 µm × 55 µm which makes it suitable for use with APD arrays. The APD is automatically reset following the end of the hold-off period. [ABSTRACT FROM PUBLISHER]

4H-SiC is an attractive material for ultraviolet detection owing to its wide band gap and a matured material technology. This paper reports the mean multiplication gain and excess noise factor with electron- and hole-initiated multiplication of a thin 4H-SiC APDs. The impact ionization coefficients for electron (α) and hole (β) using Monte Carlo method over an electric field ranging from 2000 kV/cm up to 5000 kV/cm are simulated in our work. The results show that β > α, and the ratio remains large even at very high electric field region. The electric field dependence of the impact ionization coefficients equations have been deduced from our model. Based on these equations, the avalanche breakdown voltage, multiplication gain and excess noise factor at different avalanche width have been investigated by considering the effect of dead space. As the width is increasing, the breakdown voltage and multiplication gain also increases proportionally. We observe a significantly higher multiplication gain for hole- than that of electron-initiated multiplication. The excess noise factor of electron-initiated multiplication is greater than that of hole-initiated due to higher number of feedback carriers. Thus, pure hole injection is necessary in order to ensure low excess noise in 4H-SiC APD owing to the large β > α. [ABSTRACT FROM PUBLISHER]

We implement spontaneous parametric down-conversion in temperature-stabilized PP-KTP with detection rates up to 103 photon pairs per second and μW pump power at 404 nm as a source for single photons. In this contribution we describe two applications: While in a first experiment the photon pairs will be used to implement a free-space QKD-setup based on the BB84 protocol without the need of active polarization switching, the second setup focusses on a two-photon setup based on feedback. [ABSTRACT FROM AUTHOR]

We present our recent progress in the development of semiconductor devices for photonic quantum information processing. We demonstrate the first electrically driven quantum dot entangled light source as well as a device in which we are able to tune the exciton spin splitting in order to generate entangled photon pairs. A practical and high-speed photon number detector based on a fast-gated silicon avalanche photodiode is also shown. [ABSTRACT FROM AUTHOR]

Using the correlated signal and idler photon pairs in 1550 nm band generated in 300 m dispersion shifted fiber by a pulsed pump, we measure the quantum efficiency of a InGaAs/InP avalanche photodiode based single photon detector. The measurement can be done by using photon pairs with various kinds of bandwidth. [ABSTRACT FROM AUTHOR]

The avalanche photodiode (APD) is a promising device for single-photon detection. In this study, we operated an InGaAs APD in the sub-Geiger mode. In this mode, a gate pulse is not needed; therefore, we can detect photons with asynchronous timing. The detection efficiency and the dark count rate were 2.2% and 7900 counts per second (cps), respectively. [ABSTRACT FROM AUTHOR]

Many sophisticated quantum states of light display non-classical, characteristic oscillations in their photon statistics altering with respect to the applied displacement. In order to detect these oscillations the mode matching between the studied state and the displacement field plays a crucial role. Only recently the developments in the photon counting techniques have allowed the direct measurements of the photon-number distributions of quantum states. We investigate the properties of displaced single photons by applying time-multiplexed detection of photon statistics and quantify the value of the mode overlap. [ABSTRACT FROM AUTHOR]

We introduce a counting system of up to 500 MHz for synchrotron x-ray high-rate measurements. A silicon avalanche photodiode detector was used in the counting system. The fast-pulse circuit of the amplifier was designed with hybrid ICs to prepare an ASIC system for a large-scale pixel array detector in near future. The fast amplifier consists of two cascading emitter-followers using 10-GHz band transistors. A count-rate of 3.25×108 s-1 was then achieved using the system for 8-keV x-rays. However, a baseline shift by adopting AC-coupling in the amplifier disturbed us to observe the maximum count of 4.49×108 s-1, determined by electron-bunch filling into a ring accelerator. We also report that an amplifier with a baseline restorer was tested in order to keep the baseline level to be 0 V even at high input rates. [ABSTRACT FROM AUTHOR]

Single crystal, high purity synthetic diamond is used as photoabsorption and carrier transport medium in x-ray photodiodes. While the thermal / mechanical robustness and high x-ray transmission of diamond make such devices attractive for synchrotron instrumentation, state-of-the-art quality material and electrical interfaces further make such detectors feasible. The present work develops methodology for attaining calculable responsivity (photocurrent yield) over a wide range of photon energies (0.2 to 28 keV) to within 5% accuracy. These methods achieve linear response for up to 0.2 W absorbed x-ray power and response time as low as 1 ns. Details of contact formation / robustness and bias configuration are explored. [ABSTRACT FROM AUTHOR]

In this communication we deal with a lidar system utilising an eye safe laser wavelength at 1.57 μm and an avalanche photodiode detector where it is question to optimize the SNR ratio so as to manage the detector performance when resolving the smoke plume presence. This is by considering supplement rangefinder and visibilimeter options in the considered Lidar system. [ABSTRACT FROM AUTHOR]

The information on energy spectra of 1–100 keV electrons is expected to provide an important clue to understand heating and acceleration mechanisms of magnetospheric plasmas. However, electrons of several keV to several tens of keV are not properly verified by observations owing to the problems in the measurement techniques. This study aims to bridge this gap by applying Avalanche Photodiodes (APDs) to the detection of electrons. The internal gain of APDs enables high-resolution detection of low-energy electrons down to several keV. We have tested an APD: Type spl 3989, Hamamatsu Photonics Co. Ltd. The APD responded to 2–40 keV electrons with the fine peaks of the out put pulse height distributions. Although the experiment is limited to 40 keV, electrons up to about 60 keV are predicted to be detectable with this APD from the simulation. We also have successfully made a verification test by the sounding rocket of ISAS/JAXA targeting medium energy electrons. [ABSTRACT FROM AUTHOR]

We report the use of compact InGaAs avalanche photodiodes in the first gigahertz decoy-protocol quantum key distribution to achieve a record secure key rate exceeding 1 Mbit/s for a fibre distance of 20 km. [ABSTRACT FROM AUTHOR]

BrilLanCe 380™ (LaBr3:Ce) crystal scintillators available from Saint-Gobain Crystals have achieved 2.6% FWHM for 662 keV photons. This is accomplished with PMT light sensors. Attempts to have similarly good results with PIN photo-diodes and APDs have not been successful. PIN photodiodes do not have any gain and the signal to noise ratio is poor at room temperature. Similarly, even though APDs have sufficient gain, they have poor signal to noise at room temperature. Recently there have been improvements in APDs decreasing the internal noise and increasing their sensitivity, making them an excellent light sensor. With the improved APD, it is now possible to achieve performance with a solid state light sensor comparable to that of PMTs. We have measured 2.8% for 662 keV gamma rays at room temperature using an APD for a light sensor on a 20 mm long crystal of 1.6 cc volume. APDs have advantages of compactness, inherent ruggedness and minimal sensitivity to magnetic fields. Such a device is very practical for hand held and portable field measurement applications. (Performance reported in SGC literature.) [ABSTRACT FROM AUTHOR]

Photomultiplier tubes and avalanche photodiodes, which are commonly used in quantum optic experiments, are sometimes referred to as threshold detectors because, in photon counting mode, they cannot discriminate the number of photoelectrons initially extracted from the absorber in the detector. We argue that they can be called threshold detectors on more account than that. We point out that their their functioning principle relies on two thresholds that are usually thought unimportant individually in the context of EPR-Bell discussion. We show how the combined effect of these threshold can lead to a significant sampling selection bias in the detection of pairs of pulses, resulting in an apparent violation of Bell inequalities. [ABSTRACT FROM AUTHOR]

A timing detector with silicon avalanche photodiodes (Si-APDs) has been developed for nuclear resonant scattering using synchrotron x-rays. The detector had four pairs of a germanium plate 0.1mm thick and a Si-APD (3 mm in dia., a depletion layer of 30-μm thickness). Using synchrotron x-rays of 67.4 keV, the efficiency increased to 1.5% for the incident beam, while the efficiency was 0.76 % without the germanium converters. A measurement of SR-PAC on Ni-61 was executed by using the detector. Some other types of timing detectors are planned for x-rays of E>20 keV. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

Silicon Photomultipliers (SiPM) are novel detectors for low level light detection based on arrays of avalanche photodiodes operating in Geiger mode. Offering good characteristics (fast response, high gain, photon counting capability, insensitivity to magnetic fields, low voltage operation) they have the potential to replace classical photomultipliers (PMT) in many applications. Drawbacks are dark rate and optical cross talk. Though their quantum efficiency is already comparable or better than that of bialkali PMT it is still limited by the structures on the light sensitive front surface. A new concept, presently developed at the Max-Planck semiconductor laboratory, allows boosting the efficiency to almost 100%. Using a fully depleted substrate the light enters through the unstructured backside. A drift diode structure collects the electrons on a small “point like” avalanche structure for multiplication. Engineering the thin entrance window at the backside using antireflective layers a high efficiency can be achieved in a wide wavelength range (300–1000nm). The paper will summarize the status of front illuminated SiPMs and report on the development of the backside illuminated devices. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Experiments with a cooled antiproton beam at the future accelerator facility FAIR at GSI, Darmstadt, will be performed with the 4π detector PANDA comprising a high resolution, compact and fast homogeneous electromagnetic calorimeter to detect photons between 10MeV and 10GeV energy inside a superconducting solenoid (2T). The target calorimeter comprises more than 20,000 PbWO4 crystals of significantly enhanced quality read-out with large area avalanche photodiodes at an operating temperature of -25°C. The paper describes the quality of PWO-II and illustrates the future performance based on response measurements with high-energy photons. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

This paper presents current developments for an Optical Time Domain Reflectometry (OTDR) device, based on an Avalanche Photo Diode (APD) receiver. The OTDRs for Polymer Optical Fibers (POF) are commonly based on very high sensitive photon-counting, which is quite expensive. In the proposed solution, cheaper but less sensitive optical-electrical components are used. To achieve the same sensitivity, a high number of averages is performed, implemented into Field Programmable Gate Array (FPGA) [1]. In addition the paper will show the advantages of using green laser diode (LD). [ABSTRACT FROM AUTHOR]

We demonstrate III–V avalanche photodiodes monolithically integrated onto silicon by CMOS-compatible growth. With bandwidth exceeding 3 GHz and gain as high as 28, nanopillar devices showcase the viability of bottom-up III–V nanomaterials for high-performance optoelectronics. [ABSTRACT FROM PUBLISHER]

An improved model in defining the dead time (tD) response for Silicon Avalanche Photodiode (Si APD) is presented in this paper. The generation of a mathematical model for Si APD is used to characterize the performance of passively quenched Si APD. For this purpose, quenching time (tq) and recharging time (tr) models are implemented to obtain tD less than 50 ns. Therefore, the value of quenching resistor (RL) should be minimized to reduce the recharge duration of time constant RLC. By concerning various values of RL and the influence of parasitic capacitance (C), tr and tq are analyzed in defining tD for Si APD, which is working in Geiger's mode. [ABSTRACT FROM PUBLISHER]

It is quite important to obtain wide band spectra of high energy astrophysical phenomena at the same time in order to probe emission processes or structures. Especially observations of transient objects, such as gamma-ray bursts, expect detectors with wide energy band coverage for the sake of an efficient spectroscopy within limited time windows. An avalanche photo diode (APD) is a compact photon sensor with an internal gain of ∼100. We have developed an X-ray/gamma-ray detector using a reach-through APD (5×5 mm2) optically coupled with a conventional CsI(Tl) scintillator, which covers typically from 1 keV to 1 MeV. Further, we developed a 1-dimensional array of the 8/16 APDs (net 16×20) mm2) for the purpose of an imaging photon detector combined with coded masks, to be applied in future missions. We present the current status and performances of our hybrid detector using the 8-channel array. [ABSTRACT FROM AUTHOR]

Nowadays, the superconducting single-photon detectors (SSPDs) are used in Quantum Key Distribution (QKD) instead of single-photon avalanche photodiodes. Recently bright-light control of the SSPD has been demonstrated. This attack employed a "backdoor" in the detector biasing technique. We developed the autoreset system which returns the SSPD to superconducting state when it is latched. We investigate latched state of the SSPD and define limit conditions for effective blinding attack. Peculiarity of the blinding attack is a long nonsingle photon response of the SSPD. It is much longer than usual single photon response. Besides, we need follow up response duration of the SSPD. These countermeasures allow us to prevent blind attack on SSPDs for Quantum Key Distribution. [ABSTRACT FROM AUTHOR]

We report an InAs avalanche photodiode with graded p-doping to compensate the n-type background doping in the depletion region. The measured gain, excess noise, and bandwidth are consistent with Monte Carlo simulation. [ABSTRACT FROM PUBLISHER]

Single photon detectors are one of the essential tools connecting the photonic and electronic domains at the quantum level. A plethora of single photon detector technologies and their acronyms available today - PMT, IPD, SPAD, SNSPD, MKID, RULLE, NFAD, TCB, DAPD, TES, and many others - primarily because all have significant gaps to “ideal” performance and practical usability. Some do approach ideal performance in a specific metric such as detection efficiency or dark count rate, and there is promising new progress in new material systems and new understandings of the semiconductor avalanche gain process. [ABSTRACT FROM PUBLISHER]

A silicon avalanche photodiode fabricated by CMOS process was characterized at 405 nm wavelength for Blu-ray applications. The avalanche gain of 36, the maximum responsivity of 2.61 A/W, and the bandwidth of 300 MHz were achieved. [ABSTRACT FROM PUBLISHER]

InAs electron-avalanche photodiodes are shown to produce 3 dB-bandwidth of 3.5 GHz that is not limited by the avalanche gain. Highest gain bandwidth products of 580 and 430 GHz were measured at 77 K and room temperature respectively. [ABSTRACT FROM PUBLISHER]

We demonstrate ultrafast active-quenching techniques in a silicon single-photon avalanche diode, and observe an order of magnitude reduction in afterpulsing, a factor of 1.8 reduction in diode recovery time, and increased maximum count rates. [ABSTRACT FROM PUBLISHER]

In the framework of the European FP6's BioCare project, we develop a novel photo-detector readout technique to increase sensitivity and timing precision for molecular imaging in PET and CT. Within the Project's work packages, the CERN-BioCare group focuses on the development of a PET detection head suitable to process data from both PET and CT operation in one unit. The detector module consists of a LSO matrix coupled to an APD array. The signal is processed by fast and low noise readout electronics recently developed for experiments at the Large Hadron Collider (LHC) at CERN. The functioning of this time based system is presented as well as its performances in terms of energy resolution. [ABSTRACT FROM AUTHOR]