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Simulation of waveguide integrated Ge2Sb2Te5-based tunable photodetector

optical engineering 2023年第8期62卷 087106-087106页

作者： Johari, Anoopshi Naithani, Sanjeev Kaur, Baljinder Bhatnagar, Abhinav Kaushik, Brajesh Kumar Veer Madho Singh Bhandari Uttarakhand Tech Univ THDC Inst Hydropower Engn & Technol Dept Elect & Commun Campus Inst Tehri Uttaranchal India Govind Ballabh Pant Inst Engn & Technol Dept Elect & Commun Ghurdauri Uttaranchal India Indian Inst Technol Dept Elect & Commun Roorkee Uttaranchal India Birla Inst Appl Sci Dept Elect & Commun Bhimtal Uttaranchal India

A photodetector that utilizes the phase-changing material Ge2Sb2Te5 (GST) integrated with a silicon on insulator (SOI) waveguide is designed and analyzed in the wavelength (lambda) range of 1500 to 1600 nm for telecommunication and optical fiber communication. The analysis of simulated structure reveal that GST is a promising material for photodetection applications due to phase-change property on a nano scale, excellent absorption (with an absorption coefficient of similar to 10(6) cm(-1)), lower bandgap of 0.63 ev in the amorphous phase, and 0.53 ev in the crystalline phase, tunability, and high phase stability. The photodetector structure consists of an SOI substrate, silicon waveguide, GST layer as phase changing material, and gold (Au) to make contacts. The photodetector's optical and electrical parameters, such as electric field distribution of carrier generation rate (G), absorbed power (P-abs), dark current (I-dark), photocurrent (I-ph), and responsivity (R), are analyzed for both the amorphous (a-GST) and crystalline (c-GST) phases. The results demonstrate the potential of GST material to design high-performance photodetectors for various applications. The highest resistivity of 2.29 A/W is achieved for a-GST at lambda = 1550 nm, with a bias voltage range of 0.5 to 2.5 v. The maximum absorption is observed in the amorphous phase as compared to the crystalline phase of GST. The calculated values of I-ph and I-dark are 0.24 mA and 78.54 mu A for a-GST and 0.12 mA and 15.71 mu A for c-GST, respectively. The optoelectrical behavior of GST-based photodetector on SOI waveguide demonstrates their potential application in photonic integrated circuits. Our work proposes an approach for using GST in photodetectors and analyzes both phases of GST that have not been explored before. Therefore, for the viability of the reported work, a detailed comparison is also presented with other simulated structures and found that the proposed device provided excellent results with

关键词： Ge2Sb2Te5 photodetector phase-change material waveguide finite-difference time-domain DEvICE current

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The atacama large aperture submillimetre telescope: key science drivers 11

The atacama large aperture submillimetre telescope: key scie...

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Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XI 2022

作者： Ramasawmy, Joanna Klaassen, Pamela D. Cicone, Claudia Mroczkowski, Tony K. Chen, Chian-Chou Cornish, Thomas Da Cunha, Elisabete Hatziminaoglou, Evanthia Johnstone, Doug Liu, Daizhong Perrott, Yvette Schimek, Alice Stanke, Thomas Wedemeyer, Sven UK Astronomy Technology Centre Royal Observatory Edinburgh Blackford Hill Edinburgh United Kingdom Institute of Theoretical Astrophysics University of Oslo PO Box 1029 Blindern 0315 Oslo Norway European Southern Observatory Karl-Schwarzschild-Str. 2 Garching bei Munchen85748 Germany No. 1 Sec. 4 Roosevelt Road Taipei10617 Taiwan Department of Physics Lancaster University LancasterLA1 4YB United Kingdom International Centre for Radio Astronomy Research University of Western Australia 35 Stirling Hwy CrawleyWA6009 Australia National Research Council of Canada Herzberg Astronomy and Astrophysics Research Centre 5071 West Saanich Road VictoriaBCV9E 2E7 Canada Department of Physics and Astronomy University of Victoria VictoriaBCV8P 5C2 Canada Max-Planck-Institut fur Extraterrestrische Physik Giebenbachstrabe 1 Garching b. Munchen85748 Germany School of Chemical and Physical Sciences Victoria University of Wellington PO Box 600 Wellington6140 New Zealand

ISBN: (纸本)9781510653610

The Atacama Large Aperture Submillimeter Telescope (AtLAST) is a concept for a 50m class single-dish telescope that will provide high sensitivity, fast mapping of the (sub-)millimeter sky. Expected to be powered by renewable energy sources, and to be constructed in the Atacama desert in the 2030s, AtLAST's suite of up to six stateof-the-art instruments will take advantage of its large field of view and high throughput to deliver efficient continuum and spectroscopic observations of the faint, large-scale emission that eludes current facilities. The AtLAST design study project is currently supported by a Horizon 2020 grant aimed at studying the governance, telescope design, site selection, telescope operations, sustainable energy supply, and science drivers of the future AtLAST observatory. With quantified and specific science goals, we can begin to place technical specifications on the telescope and its instrumentation. As a first step in this process, we conducted a consultation on potential AtLAST science with the global (sub-)millimeter astrophysics community. The consultation involved nearly 100 scientists based in 22 countries, and the resulting 28 use cases indicate the breadth of transformational science that such a high-throughput facility could make possible: from exploring the prebiotic molecular chemistry of comets in our own Solar System, detecting the extended, diffuse cold gas in the circumgalactic medium of both our own and distant galaxies, to detailed measurements of the thermal, kinetic, and relativistic Sunyaev-Zeldovich effect and mapping of large-scale structure. Already these science cases define some core requirements for AtLAST's instrumentation: wide bandwidths, multichroic observations, high spectral resolution, fast mapping and a large field of view. Further refinement of these is planned over the course of the current EU-funded project, resulting in detailed case studies of the telescope and instrumentation requirements needed by the comm

关键词： Site selection

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Polymeric Nanocarriers Autonomously Cross the Plant Cell Wall and Enable Protein Delivery for Stress Sensing

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ADvANCED MATERIALS 2024年第41期36卷 e2409356页

作者： Zhang, Yilin Cao, Yunteng Jiang, Wenzhi Ma, Qingquan Shin, Jinwoo Sun, Hui Cui, Jianqiao Chen, Yongsheng Giraldo, Juan Pablo Strano, Michael S. Lowry, Gregory v. Sheen, Jen Marelli, Benedetto MIT Dept Civil & Environm Engn Cambridge MA 02139 USA Harvard Med Sch Massachusetts Gen Hosp Dept Mol Biol Boston MA 02114 USA Harvard Med Sch Massachusetts Gen Hosp Ctr Computat & Integrat Biol Dept Genet Boston MA 02114 USA Georgia Inst Technol Sch Civil & Environm Engn Atlanta GA 30332 USA MIT Dept Chem Engn Cambridge MA 02139 USA Univ Calif Riverside Dept Bot & Plant Sci Riverside CA 92521 USA Carnegie Mellon Univ Dept Civil & Environm Engn Pittsburgh PA 15213 USA

Delivery of proteins in plant cells can facilitate the design of desired functions by modulation of biological processes and plant traits but is currently limited by narrow host range, tissue damage, and poor scalability. Physical barriers in plants, including cell walls and membranes, limit protein delivery to desired plant tissues. Herein, a cationic high aspect ratio polymeric nanocarriers (PNCs) platform is developed to enable efficient protein delivery to plants. The cationic nature of PNCs binds proteins through electrostatic. The ability to precisely design PNCs' size and aspect ratio allowed us to find a cutoff of approximate to 14 nm in the cell wall, below which cationic PNCs can autonomously overcome the barrier and carry their cargo into plant cells. To exploit these findings, a reduction-oxidation sensitive green fluorescent protein (roGFP) is deployed as a stress sensor protein cargo in a model plant Nicotiana benthamiana and common crop plants, including tomato and maize. In vivo imaging of PNC-roGFP enabled optical monitoring of plant response to wounding, biotic, and heat stressors. These results show that PNCs can be precisely designed below the size exclusion limit of cell walls to overcome current limitations in protein delivery to plants and facilitate species-independent plant engineering. A cationic high aspect ratio polymeric nanocarrier is developed to deliver functional protein in crops to enable species-independent plant engineering. The delivered sensor protein reduction-oxidation sensitive green fluorescent protein (roGFP) successfully monitors stressors in tobacco, tomato, and maize. This functional protein delivery platform paves the way for new technologies in plant sensing and engineering, contributing to the design of new solutions that promote plant-based sustainable development. image

关键词： nanocarrier plant engineering polymers protein delivery stress sensing

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Post-Quantum Cryptography (PQC) Network Instrument: Measuring PQC Adoption Rates and Identifying Migration Pathways

Post-Quantum Cryptography (PQC) Network Instrument: Measurin...

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Quantum Computing and engineering (QCE), IEEE International Conference on

作者： Jakub Sowa Bach Hoang Advaith Yeluru Steven Qie Anita Nikolich Ravishankar Iyer Phuong Cao National Center for Supercomputing Applications University of Illinois at Urbana-Champaign

ISBN: (数字)9798331541378

ISBN: (纸本)9798331541385

The problem of adopting quantum-resistant crypto-graphic network protocols or post-quantum cryptography (PQC) is critically important to democratizing quantum computing. The problem is urgent because practical quantum computers will break classical encryption in the next few decades. Past encrypted data has already been collected and can be de-crypted in the near future. The main challenges of adopting post-quantum cryptography lie in algorithmic complexity and hardware/software/network implementation. The grand question of how existing cyberinfrastructure will support post-quantum cryptography remains unanswered. This paper describes: i) the design of a novel Post-Quantum Cryptography (PQC) network instrument placed at the National Center for Supercomputing Applications (NCSA) at the University of Illinois at Urbana-Champaign and a part of the FABRIC testbed; ii) the latest results on PQC adoption rate across a wide spectrum of network protocols (Secure Shell - SSH, Transport Layer Security - TLS, etc.); iii) the current state of PQC implementation in key scientific applications (e.g., OpenSSH or SciTokens); iv) the challenges of being quantum-resistant; and v) discussion of potential novel attacks. This is the first large-scale measurement of PQC adoption at national-scale supercomputing centers and FABRIC testbeds. Our results show that only OpenSSH and Google Chrome have successfully implemented PQC and achieved an initial adoption rate of 0.029 % (6,044 out of 20,556,816) for OpenSSH connections at NCSA coming from major Internet Service Providers or Autonomous Systems (ASes) such as OARNET, GTT, Google Fiber Webpass (U.S.) and Uppsala Lans Landsting (Sweden), with an overall increasing adoption rate year-over-year for 2023–2024. Our analyses identify pathways to migrate current applications to be quantum-resistant.

关键词： Quantum computing Protocols Instruments current measurement Web and internet services Fabrics optical fiber LAN Internet Cryptography optical fiber testing

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A review on III-v compound semiconductor short wave infrared avalanche photodiodes

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NANOTECHNOLOGY 2022年第22期33卷 222003-222003页

作者： Liang, Yan Perumalveeramalai, Chandrasekar Lin, Guochen Su, Xiangbin Zhang, Xiaoming Feng, Shuai Xu, Yingqiang Li, Chuanbo Minzu Univ China Sch Sci Beijing 100081 Peoples R China Minzu Univ China Optoelect Res Ctr Beijing 100081 Peoples R China Chinese Acad Sci Inst Semicond Beijing 100083 Peoples R China

The on-chip avalanche photodiodes (APDs) are crucial component of a fully integrated photonics system. Specifically, III-v compound APD has become one of the main applications of optical fiber communication reception due to adaptable bandgap and low noise characteristics. The advancement of structural design and material choice has emerged as a means to improve the performance of APDs. Therefore, it is inevitable to review the evolution and recent developments on III-v compound APDs to understand the current progress in this field. To begin with, the basic working principle of APDs are presented. Next, the structure development of APDs is briefly reviewed, and the subsequent progression of III-v compound APDs (InGaAs APDs, AlxIn1-x AsySb1-y APDs) is introduced. Finally, we also discuss the key issues and prospects of AlxIn1-x AsySb1-y digital alloy avalanche APDs that need to be addressed for the future development of >= 2 mu m optical communication field.

关键词： III-v compound semiconductor avalanche photodiodes short wave infrared low noise characteristics digital alloys

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Ultra high birefringent dispersion flattened fiber in terahertz regime

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Journal of optical Communications 2023年第s1期44卷 S527-S533页

作者： Reza, Md Selim Habib, Md Ahasan Mehedi, Ibrahim Mustafa Alam, Md Mottahir Latif, Shaikh Abdul Department of Electrical and Electronic Engineering Bangabandhu Sheikh Mujibur Rahman Science and Technology University Gopalganj8100 Bangladesh King Abdulaziz University Jeddah21589 Saudi Arabia Center of Excellence in Intelligent Engineering Systems [CEIES King Abdulaziz University Jeddah21589 Saudi Arabia Nuclear Engineering Department King Abdulaziz University Jeddah21589 Saudi Arabia

In the current study, a novel Zeonex based porous core photonic crystal fiber (PC-PCF) is presented for polarization-maintaining and dispersion flattened in the terahertz (THz) region. For minimizing the Effective Material Loss (EML), an array of three rectangular and six triangular air holes are surrounded by hexagonal-shaped cladding. Finite Element Method (FEM) is employed through Comsol v5.3a software to design and examine the essential features of the proposed porous core fiber which revealed that it has an extremely small EML of 0.04 cm−1 at 1.2 THz and has almost zero flattened dispersion of 0.8 ± 0.08 ps/THz/cm in 1.0-1.4 THz frequency spectrum. Moreover, the optimum designing parameters offer an extremely high value of birefringence (0.043 at 1.2 THz). Besides, other major features notably bending loss, effective area, and confinement loss are also found to be precise and relatively low. For effective, adaptable and fitting transmission characteristics, this type of design would lay the foundations for broadband THz radiation wide variety of usage in the THz regime. © 2023 Walter de Gruyter GmbH. All rights reserved.

关键词： Birefringence

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Theoretical Performance Analysis of High-Efficiency Inx Ga1-xN/Si Tandem Solar Cells

Theoretical Performance Analysis of High-Efficiency Inx Ga1-...

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International Conference on Advancement in Electrical and Electronic engineering (ICAEEE)

作者： Md. Farhan Tanvir A.S.M. Jannatul Islam Ashraful G. Bhuiyan Department of Electrical and Electronic Engineering Khulna University of Engineering & Technology Khulna Bangladesh

ISBN: (数字)9798350388282

ISBN: (纸本)9798350388299

Owing to its intriguing optical and electrical characteristics, the $\mathrm{I}\mathrm{n}_{\mathrm{x}}\mathrm{G}\mathrm{a}1-\mathrm{x}\mathrm{N}$ alloy is being widely considered as a possible silicon (Si) combo for developing low-cost, high-efficiency multi-junction solar cells. This work reports the theoretical design and performance analysis of $\mathrm{I}\mathrm{n}_{\mathrm{x}}\mathrm{G}\mathrm{a}1-\mathrm{x}\mathrm{N}/\mathrm{S}\mathrm{i}$ double junction tandem solar cells utilizing the wxAMPS simulator. The variation of In concentration, active layer thicknesses, and doping levels are considered to achieve optimized $\mathrm{I}\mathrm{n}_{\mathrm{x}}\mathrm{G}\mathrm{a}1-\mathrm{x}\mathrm{N}/\mathrm{S}\mathrm{i}$ tandem solar cells that produce superior efficiency. Our proposed solar cells have an impressive efficiency ($\eta$) of 32.92%, a fill factor (FF) of 89.49%, a short-circuit current $(\mathrm{J}_{\mathrm{s}\mathrm{c}})$ of 12.32 $\mathrm{m}\mathrm{A}/\mathrm{c}\mathrm{m}^current$, and an excellent open-circuit voltage $(\mathrm{v}_{\mathrm{o}\mathrm{c}})$ of 2.99 v. These findings of the $\mathrm{I}\mathrm{n}_{\mathrm{x}}\mathrm{G}\mathrm{a}1-\mathrm{x}\mathrm{N}/\mathrm{S}\mathrm{i}$ tandem solar cells would be helpful for rethinking the design paradigm of present multi-junction solar cells and provide a path to achieving superior efficiency with a low-cost $\mathrm{I}\mathrm{n}_{\mathrm{x}}\mathrm{G}\mathrm{a}1-\mathrm{x}\mathrm{N}/$Si tandem structure.

关键词： Measurement Fill factor (solar cell) Photovoltaic cells Short-circuit currents Simulation voltage Silicon

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design and pre-development of an airborne multi-species differential absorption Lidar system for water vapor and HDO isotope, carbon dioxide, and methane observation

Design and pre-development of an airborne multi-species diff...

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2020 International Conference on Space Optics, ICSO 2020

作者： Dherbecourt, J.B. Raybaut, M. Melkonian, J.M. Hamperl, J. Santagata, R. Dalin, M. Lebat, v. Godard, A. Flamant, C. Totems, J. Chazette, P. Pasiskevicius, v. Heinecke, D. Schäfer, H. Strotkamp, M. Geus, J.F. Rapp, S. Sodemann, H. Steen-Larsen, H.C. DPHY ONERA Université ParisSaclay PalaiseauF-91123 France UMR 8190 CNRS-SU-UVSQ Paris France UMR 1572 CEA-CNRSUVSQ Gif-sur-Yvette France Roslagstullsbacken 21 Stockholm10691 Sweden SpaceTech GmbH Seelbachstr. 13 Immenstaad88090 Germany Fraunhofer Institute for Laser Technology Steinbachstr. 15 Aachen52074 Germany InnoLas Laser GmbH Justus-von-Liebig- Ring 8 Krailling82152 Germany Geophysical Institute University of Bergen Bjerknes Centre for Climate Research Bergen Norway

We report on the current design and preliminary developments of the airborne Lidar Emitter and Multi-species greenhouse gases Observation iNstrument (LEMON), which is aiming at probing H2O and its isotope HDO at 1982 nm, CO2 at 2051 nm, and potentially CH4 at 2290 nm, with the Differential Absorption Lidar method (DIAL). The infrared emitter is based on the combination of two Nested Cavity OPOs (NesCOPOs) with a single optical parametric amplifier (OPA) line for high-energy pulse generation. This configuration is enabled by the use of high-aperture periodically poled KTP crystals (PPKTP), which provide efficient amplification in the spectral range of interest around 2 μm with slight temperature adjustments. The parametric stages are pumped with a Nd:YAG laser providing 200 mJ nanosecond double pulses at 75 Hz. According to parametric conversion simulations supported by current laboratory experiments, output energies in the 40 - 50 mJ range are expected in the extracted signal beam whilst maintaining a good beam quality (M2 © 2021 ESA and CNES

关键词： Carbon dioxide

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design of Low-Power High-Speed Double-Tail Dynamic Comparator Based on Charge-Steering Concept

Design of Low-Power High-Speed Double-Tail Dynamic Comparato...

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2022 International Conference on Electronics Technology and Artificial Intelligence, ETAI 2022

作者： Zhang, Zhe Lei, Qianqian Zhao, Erhu Yang, Yanfei Feng, Song School of Science Xi'An Polytechnic University Xi'an710048 China Engineering Research Center of Flexible Radiation Protection Technology of Universities of Shaanxi Province Xi'an Polytechnic University Shaanxi Xi'an710048 China Dalian Boiler and Pressure Vessel Inspection & Testing Institute Co Ltd. Dalian116016 China

In this thesis, a low-power dissipation high-speed double-tail dynamic comparator is designed. Based on the principles of charge-steering, a clock charge pump is used at the tail of the latch stage to replace the clock current source, which reduce the output swing and kick-back noise of the comparator. Meanwhile, digital logic is added to the pre-amplification stage to eliminate quiescent current and further reduce power consumption. Based on the SMIC 28nm CMOS process, the proposed comparator is simulated and verified. The results show that under the condition of 0.9v supply voltage and 1MHz sampling frequency, the power dissipation is 5.4μW, the delay is 245ps, and the offset voltage is 6.9mv. Compared with a high-speed comparator, under the premise of achieving the same performance, the power consumption is reduced by 69%. © Published under licence by IOP Publishing Ltd.

关键词： Comparators (optical)

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Window size dependence of gain and bandwidth in avalanche photodiodes with multiple multiplication layers under near Geiger-mode operation

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Optics Express 2024年第14期32卷 24744-24755页

作者： Yan-Chieh Chang Ye-Kun Wu Chia-Chien Wei You-Chia Chang Tzyy-Sheng Horng Jin-Wei Shi Department of Electrical Engineering National Central Universityhttps://***/00944ve71 Jhongli 320 Taiwan Department of Photonics National Sun Yat-Sen University Kaohsiung Taiwan Department of Photonics National Yang-Ming Chiao-Tung University Hsinchu 300 Taiwan Department of Electrical Engineering National Sun Yat-Sen University Kaohsiung Taiwan

We consider avalanche photodiodes (APDs) functioning under near Geiger-mode operation for extremely weak light (single or several photons) detection, such as in LiDAR receivers. To meet such demands, APDs which simultaneously have a large active window size, moderate bandwidth (∼GHz), and high internal gain (responsivity), are highly desired. However, it is difficult to design APDs capable of meeting the afore-mentioned performance requirements due to the intrinsic limitations of the gain-bandwidth product (GBP). In this work, we demonstrate that the GBP bottleneck in the APDs can be overcome by using multiple (3) In 0.52 Al 0.48 As based multiplication (M-) layers with a thick In 0.53 Ga 0.47 As absorber (2 µm). Moreover, the characteristic invariant 3-dB bandwidth in our APDs, from low to an extremely high operation gain, becomes more pronounced with an increase of its active window diameter (40 to 200 µm). This characteristic makes it very attractive for collecting weak light in free space as is required for LIDAR receiver applications. Comparison shows that the 200 µm APD exhibits a higher 0.9 v br responsivity (15 vs. 7 A/W), larger maximum gain (460 vs. 110), and higher GBP (468 vs. 131 GHz) than does the 40 µm reference sample and can sustain a constant 3-dB bandwidth (1.4 GHz) over a wide range of operation gains (10 to 460). The dependence of the APD performance on the window size can be attributed to the influence of the surface states on the edge of the etched mesa. Here, we further demonstrate a backside-illuminated structure with a flip-chip bonding package which minimizes this phenomenon in small APDs ensuring high-speed performance. Compared with the top-illuminated reference samples, the flip-chip bonding packaged device shows a further enhancement of the responsivity (10.7 vs. 7 A/W), 3-dB bandwidth (4.1 vs. 3.9 GHz), and saturation current (4.25 vs. 3.6 mA). The excellent static and dynamic performance of our flip-chip APD in turn leads to an unpre

关键词： Avalanche photodiodes Detectors Lidar optical absorption optical detection optical pumping

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