• Title/Summary/Keyword: single-photon detection

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Effect of two-photon spatial bunching on single photon detection rates (광자쌍의 뭉침현상이 단일계수에 미치는 영향)

  • 김헌오;신하림;박구동;김태수
    • Korean Journal of Optics and Photonics
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    • v.14 no.6
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    • pp.573-577
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    • 2003
  • We report an effect of photon pairs on single-photon detection rates, while Hong-Ou-Handel's two-photon interference experiment is performed with photons produced in noncollinear type-I parametric down-conversion. Photon pairing behavior or spatial bunching is measured and shown to cause a decrease in the single photon counting rate. Such a dip is found to result from the fact that the single-photon timing resolution of photodetectors is much longer compared to the time interval between the two photons incident on the single-photon detector.

Improved Circuits for Single-photon Avalanche Photodiode Detectors

  • Kim, Kyunghoon;Lee, Junan;Song, Bongsub;Burm, Jinwook
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.14 no.6
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    • pp.789-796
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    • 2014
  • A CMOS photo detection bias quenching circuit is developed to be used with single photon avalanche photodiodes (SPADs) operating in Geiger mode for the detection of weak optical signals. The proposed bias quenching circuits for the performance improvement reduce the circuit size as well as improve the performance of the quenching operation. They are fabricated in a $0.18-{\mu}m$ standard CMOS technology to verify the effectiveness of this technique with the chip area of only $300{\mu}m^2$, which is about 60 % of the previous reported circuit. Two types of proposed circuits with resistive and capacitive load demonstrated improved performance of reduced quenching time. With a commercial APD by HAMAMATSU, the dead time can be adjusted as small as 50 ns.

Optical Characterization of Superconducting Strip Photon Detector Using $MgB_2$

  • Shibata, H.
    • Progress in Superconductivity
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    • v.14 no.2
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    • pp.96-98
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    • 2012
  • Bias current dependence of a superconducting strip photon detector is studied in the wavelength range of 405 to 1310 nm. The detector is made of an $MgB_2$ meander pattern with the line width of 135 nm and thickness of 10 nm. At 1310 nm, the detection efficiency exponentially decreases as the bias current decreases. While at 405 nm, the detection efficiency almost saturates in the high bias current region. These features suggest that the intrinsic detection efficiency of the $MgB_2$ detector is high at 405 nm.

Design of an Antireflection Coating for High-efficiency Superconducting Nanowire Single-photon Detectors

  • Choi, Jiman;Choi, Gahyun;Lee, Sun Kyung;Park, Kibog;Song, Woon;Lee, Dong-Hoon;Chong, Yonuk
    • Current Optics and Photonics
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    • v.5 no.4
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    • pp.375-383
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    • 2021
  • We present a simulation method to design antireflection coating (ARCs) for fiber-coupled superconducting nanowire single-photon detectors. Using a finite-element method, the absorptance of the nanowire is calculated for a defined unit-cell structure consisting of a fiber, ARC layer, nanowire absorber, distributed Bragg reflector (DBR) mirror, and air gap. We develop a method to evaluate the uncertainty in absorptance due to the uncontrollable parameter of air-gap distance. The validity of the simulation method is tested by comparison to an experimental realization for a case of single-layer ARC, which results in good agreement. We show finally a double-layer ARC design optimized for a system detection efficiency of higher than 95%, with a reduced uncertainty due to the air-gap distance.

A brief review on the recent progress of superconducting nanowire single photon detectors

  • Chong, Yonuk
    • Progress in Superconductivity and Cryogenics
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    • v.19 no.4
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    • pp.22-25
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    • 2017
  • Superconducting nanowire single photon detectors (SNSPD) have become the most competent photon-counting devices in wide range of wavelengths. Especially in the communication wavelength (infrared), SNSPD has shown unbeatable superior performance compared to the state-of-art semiconductor single photon detectors. The technology has matured enough for the last decade so that several commercial systems are now almost ready for routine use in general optics experiments. Here we summarize briefly the recent progress in this research field, and hope to motivate further research on the improvement of the device and the system. We cover the basic key concepts, device and system performances, remaining issues and possible further research directions of SNSPD.

Characterization of small single photon avalanche diode fabricated using standard 180 nm CMOS process for digital SiPM

  • Jinseok Oh;Hakcheon Jeong;Min Sun Lee;Inyong Kwon
    • Nuclear Engineering and Technology
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    • v.56 no.8
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    • pp.3076-3083
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    • 2024
  • In this work, single photon avalanche diodes (SPADs) were fabricated using the standard 180 nm complementary metal-oxide semiconductor process. Their small size of 15-16 µ m and low operating voltage made it possible to easily integrate them with readout circuits for compact on-chip sensors, particularly those used in the radiation sensor network of a nuclear plant. Four architectures were proposed for the SPADs, with a shallow trench isolation (STI) guard ring and different depletion regions designed to demonstrate the main performance parameters in each experimental configuration. The wide absorption region structure with PSD and a deep N-well could achieve a uniform electric field, resulting in a stable dark count rate (DCR). Additionally, the STI guard ring was implanted to mitigate the premature edge breakdown. A breakdown voltage was achieved for a low operating voltage of 10.75 V. The DCR results showed 286.3 Hz per ㎛2 at an excess voltage of 0.04 V. A photon detection probability of 21.48% was obtained at 405 nm.

Fluorescence photon counting rate as a function of dye concentration: Effect of dead time of photon detector (색소 농도에 따른 형광 광자의 계수율 : 광자 검출기의 dead time 효과)

  • 고동섭
    • Korean Journal of Optics and Photonics
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    • v.8 no.4
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    • pp.353-355
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    • 1997
  • A single molecule detection system, which consists of confocal fluorescence microscope and single photon counter, has been used to observe the dye concentration dependence of photon counting rate. With increasing concentration, a saturation effect of counting is observed and demonstrated on the basis of the dead time of photon detector. The equations presented here show the relations between the counting rate and some parameters such as probe volume, quantum efficiency of detector, and fluorescence photon number entered onto detector. The signal-to-noise ratio is also discussed briefly.

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Single-photon Detection at 1.5 ㎛ Telecommunication Wavelengths Using a Frequency up-conversion Detector (주파수 상향변환 검출기를 이용한 1.5 ㎛ 통신파장대역의 단일광자 측정)

  • Kim, Heon-Oh;Youn, Chun-Ju;Cho, Seok-Beom;Kim, Yong-Soo
    • Korean Journal of Optics and Photonics
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    • v.22 no.5
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    • pp.223-229
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    • 2011
  • We present a low jitter frequency up-conversion detector based on quasi-phase matched sum frequency generation in a periodically poled $LiNbO_3$ waveguide for efficient single-photon detection at 1.5 ${\mu}m$ telecommunication wavelengths. The maximum detection efficiency and the noise count rate using the pump power of 300 mW and the pump wavelength of 974 nm are about 7% and 480 kHz, respectively. We also characterize the timing jitter of the frequency up-conversion detector by analyzing the time distribution of the detection outputs for photons generated through a picosecond pump pulsed spontaneous parametric downconversion. The minimum timing jitter was measured to be about 39.1 ps. Coincidence measurement with a narrow time window for pulsed up-conversion photons can eliminate the unwanted noise counts and maximize signal to noise ratio.

Changing Role of Nuclear Medicine for the Evaluation of Focal Hepatic Tumors: From Lesion Detection to Tissue Characterization (국소 간 종양의 조직적 특성을 평가하는데 있어 최근 핵의학의 역할)

  • Kim, Chun-Ki;Yu, Mi-Jin
    • The Korean Journal of Nuclear Medicine
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    • v.32 no.3
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    • pp.211-224
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    • 1998
  • The role of scintigraphic imaging has moved from the detection of lesions to the tissue-specific characterization of lesions over the past 2 decades. Major advances in nuclear medicine imaging include: 1) positron imaging, 2) improved instrumentation, such as the use of multidetector (dual or triple head) gamma cameras for single photon emission computed tomography, and 3) development of numerous new radiopharmaceuticals for positron or single photon imaging (labeled glucose analogue, amino acids, fatty acids, hormones, drugs, receptor ligands, monoclonal antibodies, etc). These advances have resulted in a significantly improved efficacy of radionuclide techniques for the evaluation of various tumors, including those within the liver. The current role of nuclear medicine in the evaluation of focal hepatic tumors is reviewed in this article with an emphasis on the clinical applications of various tracer studies and imaging findings.

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