Phase Diversity Electro-optic Sampling: A new approach to single-shot terahertz waveform recording

AbstractRecording electric field evolution in single-shot with THz bandwidth is needed in science including spectroscopy, plasmas, biology, chemistry, Free-Electron Lasers, accelerators, and material inspection. However, the potential application range depends on the possibility to achieve sub-picosecond resolution over a long time window, which is a largely open problem for single-shot techniques. To solve this problem, we present a new conceptual approach for the so-called spectral decoding technique, where a chirped laser pulse interacts with a THz signal in a Pockels crystal, and is analyzed using a grating optical spectrum analyzer. By borrowing mathematical concepts from photonic time stretch theory and radio-frequency communication, we deduce a novel dual-output electro-optic sampling system, for which the input THz signal can be numerically retrieved—with unprecedented resolution—using the so-called phase diversity technique. We show numerically and experimentally that this approach enables the recording of THz waveforms in single-shot over much longer durations and/or higher bandwidth than previous spectral decoding techniques. We present and test the proposed DEOS (Diversity Electro-Optic Sampling) design for recording 1.5 THz bandwidth THz pulses, over 20 ps duration, in single-shot. Then we demonstrate the potential of DEOS in accelerator physics by recording, in two successive shots, the shape of 200 fs RMS relativistic electron bunches at European X-FEL, over 10 ps recording windows. The designs presented here can be used directly for accelerator diagnostics, characterization of THz sources, and single-shot Time-Domain Spectroscopy.

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Time Window from Visual Images to Visual Short-Term Memory: Consolidation or Integration?

Experimental Psychology (formerly Zeitschrift für Experimentelle Psychologie) ◽

10.1027/1618-3169.51.1.45 ◽

2004 ◽

Vol 51 (1) ◽

pp. 45-51 ◽

Cited By ~ 21

Author(s):

Yuhong Jiang

Keyword(s):

Short Term Memory ◽

Time Window ◽

Short Interval ◽

Visual Images ◽

Short Term ◽

Temporal Window ◽

Term Memory ◽

Visual Short Term Memory ◽

Probe Task ◽

Long Time

Abstract. When two dot arrays are briefly presented, separated by a short interval of time, visual short-term memory of the first array is disrupted if the interval between arrays is shorter than 1300-1500 ms ( Brockmole, Wang, & Irwin, 2002 ). Here we investigated whether such a time window was triggered by the necessity to integrate arrays. Using a probe task we removed the need for integration but retained the requirement to represent the images. We found that a long time window was needed for performance to reach asymptote even when integration across images was not required. Furthermore, such window was lengthened if subjects had to remember the locations of the second array, but not if they only conducted a visual search among it. We suggest that a temporal window is required for consolidation of the first array, which is vulnerable to disruption by subsequent images that also need to be memorized.

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Robust speaker verification using short-time frequency with long-time window and fusion of multi-resolutions

10.21437/interspeech.2008-502 ◽

2008 ◽

Author(s):

Chien-Lin Huang ◽

Bin Ma ◽

Chung-Hsien Wu ◽

Brian Mak ◽

Haizhou Li

Keyword(s):

Time Window ◽

Speaker Verification ◽

Time Frequency ◽

Long Time ◽

Short Time

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Feasibility study of a single-shot 3D electron bunch shape monitor with an electro-optic sampling technique

Physical Review Special Topics - Accelerators and Beams ◽

10.1103/physrevstab.16.052801 ◽

2013 ◽

Vol 16 (5) ◽

Cited By ~ 4

Author(s):

Yuichi Okayasu ◽

Hiromitsu Tomizawa ◽

Shinichi Matsubara ◽

Noritaka Kumagai ◽

Akira Maekawa ◽

...

Keyword(s):

Feasibility Study ◽

Electron Bunch ◽

Sampling Technique ◽

Single Shot ◽

Electro Optic ◽

3D Electron

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A single‐shot autocorrelator for the ultraviolet with a variable time window

Review of Scientific Instruments ◽

10.1063/1.1141207 ◽

1990 ◽

Vol 61 (3) ◽

pp. 998-1003 ◽

Cited By ~ 14

Author(s):

S. Szatmári ◽

F. P. Schäfer ◽

J. Jethwa

Keyword(s):

Time Window ◽

Single Shot ◽

Variable Time

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Evolution of andrenine bees reveals a long and complex history of faunal interchanges between the Americas during the Mesozoic and Cenozoic

10.1101/2021.08.05.455338 ◽

2021 ◽

Author(s):

Kelli S Ramos ◽

Aline C Martins ◽

Gabriel A R Melo

Keyword(s):

North America ◽

South America ◽

Time Window ◽

Distributional Pattern ◽

Long Distance ◽

Early Diversification ◽

Palearctic Region ◽

Long Time ◽

The Times ◽

Dated Phylogeny

Bees are presumed to have arisen in the early to mid-Cretaceous coincident with the fragmentation of the southern continents and concurrently with the early diversification of the flowering plants. Among the main groups of bees, Andreninae sensu lato comprise about 3000 species widely distributed with greatest and disjunct diversity in arid areas of North America, South America, and the Palearctic region. Here, we present the first comprehensive dated phylogeny and historical biogeographic analysis for andrenine bees, including representatives of all currently recognized tribes. Our analyses rely on a dataset of 106 taxa and 7952 aligned nucleotide positions from one mitochondrial and six nuclear loci. Andreninae is strongly supported as a monophyletic group and the recovered phylogeny corroborates the commonly recognized clades for the group. Thus, we propose a revised tribal classification that is congruent with our phylogenetic results. The time-calibrated phylogeny and ancestral range reconstructions of Andreninae reveal a fascinating evolutionary history with Gondwana patterns that are unlike those observed in other subfamilies of bees. Andreninae arose in South America during the Late Cretaceous around 90 Million years ago (Ma) and the origin of tribes occurred through a relatively long time-window from this age to the Miocene. The early evolution of the main lineages took place in South America until the beginning of Paleocene with North American fauna origin from it and Palearctic from North America as results of multiple lineage interchanges between these areas by long-distance dispersal or hopping through landmass chains. Overall, our analyses provide strong evidence of amphitropical distributional pattern currently observed in Andreninae in the American continent as result at least three periods of possible land connections between the two American landmasses, much prior to the Panama Isthmus closure. The andrenine lineages reached the Palearctic region through four dispersal events from North America during the Eocene, late Oligocene and early Miocene, most probably via the Thulean Bridge. The few lineages with Afrotropical distribution likely originated from a Palearctic ancestral in the Miocene around 10 Ma when these regions were contiguous, and the Sahara Desert was mostly vegetated making feasible the passage by several organisms. Incursions of andrenine bees to North America and then onto the Old World are chronological congruent with distinct periods when open-vegetation habitats were available for trans-continental dispersal and at the times when aridification and temperature decline offered favorable circumstances for bee diversification.

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Asymmetric Residual Neural Network for Accurate Human Activity Recognition

Information ◽

10.3390/info10060203 ◽

2019 ◽

Vol 10 (6) ◽

pp. 203 ◽

Cited By ~ 2

Author(s):

Jun Long ◽

Wuqing Sun ◽

Zhan Yang ◽

Osolo Ian Raymond

Keyword(s):

Activity Recognition ◽

Human Activity ◽

Time Window ◽

Research Problem ◽

Human Activity Recognition ◽

Sensor Data ◽

Practical Applications ◽

Long Time ◽

Benchmark Datasets ◽

High Level

Human activity recognition (HAR) using deep neural networks has become a hot topic in human–computer interaction. Machines can effectively identify human naturalistic activities by learning from a large collection of sensor data. Activity recognition is not only an interesting research problem but also has many real-world practical applications. Based on the success of residual networks in achieving a high level of aesthetic representation of automatic learning, we propose a novel asymmetric residual network, named ARN. ARN is implemented using two identical path frameworks consisting of (1) a short time window, which is used to capture spatial features, and (2) a long time window, which is used to capture fine temporal features. The long time window path can be made very lightweight by reducing its channel capacity, while still being able to learn useful temporal representations for activity recognition. In this paper, we mainly focus on proposing a new model to improve the accuracy of HAR. In order to demonstrate the effectiveness of the ARN model, we carried out extensive experiments on benchmark datasets (i.e., OPPORTUNITY, UniMiB-SHAR) and compared the results with some conventional and state-of-the-art learning-based methods. We discuss the influence of networks parameters on performance to provide insights about its optimization. Results from our experiments show that ARN is effective in recognizing human activities via wearable datasets.

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Single-Shot Electro-Optic Sampling on the Temporal Structure of Laser Wakefield Accelerated Electrons

Crystals ◽

10.3390/cryst10080640 ◽

2020 ◽

Vol 10 (8) ◽

pp. 640

Author(s):

Kai Huang ◽

Hideyuki Kotaki ◽

Michiaki Mori ◽

Yukio Hayashi ◽

Nobuhiko Nakanii ◽

...

Keyword(s):

Real Time ◽

Temporal Structure ◽

High Energy ◽

High Energy Particle ◽

Single Shot ◽

Generation Process ◽

Laser Wakefield Acceleration ◽

Wakefield Acceleration ◽

Electro Optic ◽

Laser Wakefield

Particle acceleration driven by a high power Ti: sapphire laser has invoked great interest worldwide because of the ultrahigh acceleration gradient. For the aspect of electron acceleration, electron beams with energies over GeV have been generated using the laser wakefield acceleration mechanism. For the optimization of the electron generation process, real-time electron parameter monitors are necessary. One of the key parameters of a high energy particle beam is the temporal distribution, which is closely related with the timing resolution in a pump-probe application. Here, we introduced the electro-optic sampling method to laser wakefield acceleration. Real-time multibunch structures were observed. Careful calculations on the physical processes of signal generation in an electro-optic crystal were performed. Discussions of the methodology are elaborated in detail.

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