1,299 research outputs found
Integrated high-performance timing electronics for Time Correlated Single Photon Counting with SPAD Arrays
No full textBeyond pile-up limits in Time Correlated Single Photon Counting: a new approach
No full textThe Time Correlated Single Photon Counting (TCSPC) technique has gained a prominent role in the analysis of fast and faint optical signals. Nonetheless, it has been historically considered an intrinsically slow technique due to its repetitive nature combined with a strict constraint on the maximum detector count rate to avoid distortion. Indeed, classic TCSPC theory states that low (preferably negligible) distortion can be achieved only by limiting the single-photon detector count rate down to few percent (typically 1-5%) of the laser excitation rate[1]. In 2017, we demonstrated an alternative path to avoid distortion in TCSPC based on matching the detector dead time to the excitation period. This approach still limits the speed, preventing the exploitation of the fastest single photon detectors, e.g. Single Photon Avalanche Diodes with a dead time of a few nanoseconds. In this work, we present the experimental validation of a novel TCSPC methodology [2] showing how it is possible to remove all constraints (power, dead time, etc). and still get a negligible level of distortion. This approach opens the way to unprecedented speed in TCSPC measurement
4.3ps rms jitter time to amplitude converter in 350nm Si-Ge technology
No full textNowadays, many applications require the measurement of a time interval: while a coarse timing information down to the nanoseconds range can be easily obtained with a counter, achieving a precision in the order of few picoseconds require more complex circuits, especially if high linearity and operating rates up to tens of Mcps are also necessary. In this paper, we show preliminary results on a new fully integrated time to amplitude converter designed in 350nm Si-Ge technology. The circuit is able to provide a timing precision as low as 4.3ps rms on a 12.5ns full scale range and a linearity better than 1% rms
37ps-Precision Time-Resolving Active Quenching Circuit for High-Performance Single Photon Avalanche Diodes
No full textTime-resolved imaging by means of single-photon avalanche diodes (SPADs) has achieved widespread interest in recent years, especially since technological progress has opened the way to the development of multichannel time-correlated single-photon counting (TCSPC) acquisition systems. Unfortunately, currently available TCSPC imagers feature relatively low performance with respect to state-of-the-art single-channel systems. A real breakthrough in this field would be the exploitation of large arrays of high-performance SPAD detectors developed by means of dedicated fabrication processes, usually referred to as custom technology. Custom-technology SPADs require external electronics potentially leading to interconnection issues for densely integrated arrays. In this paper, we present a new fully integrated front-end circuit able to provide both quenching/reset and timing functionalities while requiring a single connection toward the SPAD. This is the first fully integrated circuit reported in literature that can provide both the timing information about the photon time of arrival with a jitter as low as 37 ps and apply high-voltage pulses up to 50 V in order to meet the requirements of several detectors, including the new red-enhanced SPAD. Combining these two capabilities in a single circuit strongly reduces the complexity of the connection between an array of custom-technology SPADs and the relative external front end, thus paving the way for the exploitation of high-performance SPADs in TCSPC imaging systems
Single-photon avalanche diodes: state of the art and perspectives in quantum applications
No full textSingle-photon detectors play a prominent role in quantum photonics. In this field, superconducting nanowire single-photon detectors (SNSPDs) excel in terms of performance, but their application is often limited by the necessity of cryogenic temperatures. Single-photon avalanche diodes (SPADs) represent an alternative in all these situations. Here, we focus on the progress made on silicon SPADs, whose performance in the visible range provide a valid option for several quantum applications, and, after that, we review the novel solutions that are blossoming for the telecom optical bands. In the end, we conclude with our vision of SPADs in quantum photonics applications
Toward Constraintless Time-Correlated Single-Photon Counting Measurements: A New Method to Remove Pile-up Distortion
No full textTime-Correlated Single-Photon Counting (TCSPC) is a well-renowned technique allowing to reconstruct light signals with high sensitivity and resolution. Nevertheless, to this day, its use in applications requiring a fast analysis of the sample is limited due to its long acquisition time. The reason is twofold: on one hand, it is based on a statistical method thus requiring the collection of a large number of events to properly reconstruct the signal waveform; on the other hand, the average number of photons impinging on the sensor has to be kept particularly low to avoid artifacts. Indeed, the existence of dead time of both single-photon detectors and electronics can lead to distortion in the reconstructed waveform, which can be mitigated only if the count rate is kept below few percent of the excitation frequency. Recently, it has been demonstrated that an appropriate tuning of detector dead time allows to remove such power restriction, but, unfortunately, this constraint also sets a limit to the maximum count rate of the detector. In this paper, we present a novel method for TCSPC measurements, which ensures negligible distortion at unprecedented rates without requiring any constraint on either illumination power or detector dead time. We will show that this is possible thanks to the acquisition of additional information on the status of TCSPC system. The theoretical analysis reported in this paper is supported by analytical computation and numerical simulation, taking into account also potential non idealities of a real implementation
Transfer Bandwidth Optimization for Multichannel Time-Correlated Single-Photon-Counting Systems Using a Router-Based Architecture: New Advancements and Results
No full textTime-correlated single-photon counting (TCSPC) is a powerful technique for time-resolved measurement of fast and weak light signals used in a variety of scientific fields, including biology, medicine, and quantum cryptography. Unfortunately, given its repetitive nature, TCSPC is recognized as a relatively slow technique. In the last ten years, attempts have been made to speed it up by developing multichannel integrated architectures. Yet, for the solutions proposed thus far, the measurement speed has not increased proportionally to the number of channels, reducing the benefits of a multichannel approach. Recent theoretical studies and prototypes have shown that it is possible to implement a new multichannel architecture, so-called router-based architecture, capable of optimizing the efficiency of data transfer from the integrated chip to the data processor, increasing the overall measurement speed. However, the first implementations failed to achieve the theoretical results due to implementation flaws. In this paper, we present a new logic for the router-based architecture that can operate at the same laser frequency and solve the issues of the previous implementation. Alongside the new logic, we present a new integrated low-jitter delay line combined with a new method for timing-signal distribution that allows the proper management of the pixel timing information. The new implementation is a step closer to realizing a router-based architecture that achieves the expected theoretical results. Simulations and bench tests support the results here reported
Timing measurements with Single Photon Avalanche Diodes: principles and perspectives
No full textPicosecond timing of single photons has laid the foundation of a great variety of applications, from life sciences to quantum communication, thanks to the combination of ultimate sensitivity with a bandwidth that cannot be reached by analog recording techniques. Nowadays, more and more applications could still be enabled or advanced by progress in the available instrumentation, resulting in a steadily increasing research interest in this field. In this scenario, single-photon avalanche diodes (SPADs) have gained a key position, thanks to the remarkable precision they are able to provide, along with other key advantages like ruggedness, compactness, large signal amplitude, and room temperature operation, which neatly distinguish them from other solutions like superconducting nanowire single-photon detectors and silicon photomultipliers. With this work, we aim at filling a gap in the literature by providing a thorough discussion of the main design rules and tradeoffs for silicon SPADs and the electronics employed along them to achieve high timing precision. In the end, we conclude with our outlook on the future by summarizing new routes that could benefit from present and prospective timing features of silicon SPADs
Overcoming Pile-up Limitation in Fluorescence Lifetime Imaging
No full textWe present the first compact Time-Correlated Single-Photon Counting single-channel system, capable of overcoming the typical pile-up limitation of Fluorescence Lifetime Imaging. An ultra-fast acquisition is obtained (40 Mcps), along with excellent timing results and negligible distortion
Time-Correlated Single-Photon Counting Measurements: A New Approach for High-Speed
No full textWhen high timing resolution and extremely low sensitivity are needed for the analysis of optical signals, Time-Correlated Single-Photon Counting (TCSPC) is one of the preferred techniques [1]. Fluorescence Lifetime Imaging (FLIM) and single-molecule analysis are examples of applications in which these features, together with non-invasivity, are fundamental. Unfortunately, long acquisition time characterises this technique, preventing its use in many other advanced applications, where real time imaging is needed. To make the situation even worse, there is an ultimate limit on the excitation rate, which is imposed by the so called classic pile-up. Indeed, in a TCSPC measurement, it is the major source of distortion, since it allows the system to record only first impinging photons, losing the subsequent; for this reason the count rate of each acquisition channel is kept between 1%-5% of the laser repetition rate
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