Pub Date : 2023-10-12DOI: 10.1088/1361-6463/acff07
HAITAO JIA, ZHEN CHEN, WEIXIAN YU, Changshui Chen
Abstract In this paper, a nonlinear optical cascaded difference frequency generation model based on double rapid adiabatic passage technique is established, and a theoretical scheme for generating THz waves based on the above model is proposed. In this model, when the incident signal laser interacts with a pump laser, the signal laser can be completely converted into the output laser by special processing of the coupling wave equation and making reasonable assumptions. Numerical simulation results show that THz waves with a centre frequency of 260 GHz can be obtained. The maximum quantum conversion efficiency of the signal laser to THz waves is about 43.4%. Under the premise of keeping the wavelength of the pump laser unchanged, the tunable THz waves of 0.26–2.94 THz can be obtained when tuning the wavelength of the signal laser to change in the range of 1.054–1.064 μ m. Compared with the scheme using stimulated Raman adiabatic passage technique, the scheme can still generate terahertz waves during the application of a pump laser to two simultaneous difference frequency generation processes, and the intensity of the pump laser can be reduced from Gigawatt level to Megawatt level. This scheme is robust to the temperature variation and provides a new method for generating terahertz wave band for high-speed wireless transmission.
{"title":"Generation of terahertz waves based on nonlinear frequency conversion with double rapid adiabatic passage technique","authors":"HAITAO JIA, ZHEN CHEN, WEIXIAN YU, Changshui Chen","doi":"10.1088/1361-6463/acff07","DOIUrl":"https://doi.org/10.1088/1361-6463/acff07","url":null,"abstract":"Abstract In this paper, a nonlinear optical cascaded difference frequency generation model based on double rapid adiabatic passage technique is established, and a theoretical scheme for generating THz waves based on the above model is proposed. In this model, when the incident signal laser interacts with a pump laser, the signal laser can be completely converted into the output laser by special processing of the coupling wave equation and making reasonable assumptions. Numerical simulation results show that THz waves with a centre frequency of 260 GHz can be obtained. The maximum quantum conversion efficiency of the signal laser to THz waves is about 43.4%. Under the premise of keeping the wavelength of the pump laser unchanged, the tunable THz waves of 0.26–2.94 THz can be obtained when tuning the wavelength of the signal laser to change in the range of 1.054–1.064 μ m. Compared with the scheme using stimulated Raman adiabatic passage technique, the scheme can still generate terahertz waves during the application of a pump laser to two simultaneous difference frequency generation processes, and the intensity of the pump laser can be reduced from Gigawatt level to Megawatt level. This scheme is robust to the temperature variation and provides a new method for generating terahertz wave band for high-speed wireless transmission.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135922869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-12DOI: 10.1088/1361-6463/acfe87
Joachim Lauwens, Lars Kerkhofs, Arnau Sala, Bart Soree
Abstract Electronic devices that work in the quantum regime often employ hybrid nanostructures to bring about a nonlinear behaviour. The nonlinearity that these can provide has proven to be useful, in particular, for applications in quantum computation. Here we present a hybrid device that acts as a capacitor with a nonlinear charge–voltage relation. The device consists of a nanowire placed between the plates of a coplanar capacitor, with a co-parallel alignment. At low temperatures, due to the finite density of states on the nanowire, the charge distribution in the capacitor is uneven and energy-dependent, resulting in a charge-dependent effective capacitance. We study this system analytically and numerically, and show that the nonlinearity of the capacitance is significant enough to be utilized in circuit quantum electrodynamics. The resulting nonlinearity can be switched on, modulated, and switched off by an external potential, thus making this capacitive device highly versatile for uses in quantum computation.
{"title":"Superconductor-semiconductor hybrid capacitance with a nonlinear charge-voltageprofile","authors":"Joachim Lauwens, Lars Kerkhofs, Arnau Sala, Bart Soree","doi":"10.1088/1361-6463/acfe87","DOIUrl":"https://doi.org/10.1088/1361-6463/acfe87","url":null,"abstract":"Abstract Electronic devices that work in the quantum regime often employ hybrid nanostructures to bring about a nonlinear behaviour. The nonlinearity that these can provide has proven to be useful, in particular, for applications in quantum computation. Here we present a hybrid device that acts as a capacitor with a nonlinear charge–voltage relation. The device consists of a nanowire placed between the plates of a coplanar capacitor, with a co-parallel alignment. At low temperatures, due to the finite density of states on the nanowire, the charge distribution in the capacitor is uneven and energy-dependent, resulting in a charge-dependent effective capacitance. We study this system analytically and numerically, and show that the nonlinearity of the capacitance is significant enough to be utilized in circuit quantum electrodynamics. The resulting nonlinearity can be switched on, modulated, and switched off by an external potential, thus making this capacitive device highly versatile for uses in quantum computation.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135923000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-12DOI: 10.1088/1361-6463/acffd6
Gang Wang, Fanbo Ji, Jiang Li, Xinmiao Zhang, hongchang wu, zhaowen Bai, Mengjing Jin, Jin Yuan Zhou, Erqing Xie, Xiao Jun Pan
Abstract Flexible ultraviolet (UV) photodetector exhibits a promising application in portable electronic gadgets, display devices and biomedical imaging. In this study, a flexible photoanode of the photoelectrochemical (PEC)-type UV photodetector based on rutile TiO 2 nanowires (TiO 2 NWs) grown on carbon fiber cloth is realized. In photovoltaic applications, an insulating layer is usually introduced to suppress interfacial recombination and reduce the surface trap states. The interfacial recombination of semiconductor/electrolyte is suppressed by coating an Al 2 O 3 barrier layer on the TiO 2 NWs. The photodetectors of the TiO 2 @Al 2 O 3 NWs show stable photocurrent, a high light/dark current ratio ( I light / I dark ) of 1170, a faster rise and decay response times of 0.09 and 0.09 s, and excellent spectral selectivity from 300 to 400 nm. The peak responsivity of the photodetectors reaches 2.8 mA W −1 at 360 nm. This flexible photoanode have a potential application in wearable PEC UV photodetector.
{"title":"Preparation of a flexible photoanode of the photoelectrochemical ultraviolet photodetector based on rutile TiO<sub>2</sub> nanowires and the suppressed charge recombination at solid/liquid interface","authors":"Gang Wang, Fanbo Ji, Jiang Li, Xinmiao Zhang, hongchang wu, zhaowen Bai, Mengjing Jin, Jin Yuan Zhou, Erqing Xie, Xiao Jun Pan","doi":"10.1088/1361-6463/acffd6","DOIUrl":"https://doi.org/10.1088/1361-6463/acffd6","url":null,"abstract":"Abstract Flexible ultraviolet (UV) photodetector exhibits a promising application in portable electronic gadgets, display devices and biomedical imaging. In this study, a flexible photoanode of the photoelectrochemical (PEC)-type UV photodetector based on rutile TiO 2 nanowires (TiO 2 NWs) grown on carbon fiber cloth is realized. In photovoltaic applications, an insulating layer is usually introduced to suppress interfacial recombination and reduce the surface trap states. The interfacial recombination of semiconductor/electrolyte is suppressed by coating an Al 2 O 3 barrier layer on the TiO 2 NWs. The photodetectors of the TiO 2 @Al 2 O 3 NWs show stable photocurrent, a high light/dark current ratio ( I light / I dark ) of 1170, a faster rise and decay response times of 0.09 and 0.09 s, and excellent spectral selectivity from 300 to 400 nm. The peak responsivity of the photodetectors reaches 2.8 mA W −1 at 360 nm. This flexible photoanode have a potential application in wearable PEC UV photodetector.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135923444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-12DOI: 10.1088/1361-6463/ad0060
Guoqiang Liu, Yang Xia, Kefeng Shang, Dongping Liu
Abstract Atmospheric pressure plasma jets (APPJs) produce reactive species and electric fields for biomedical applications. Gas shields control plasma plume-surrounding gas interactions, regulating reactive species generation and electric field strength. However, the surface electric field distribution is still unclear and needs urgent attention. Here, the electric field distribution on the surface exposed to a helium APPJ with shielding gas is investigated using the Pockels technique. This study considers the influence of the type of shielding gas (ambient air, dry air, nitrogen, oxygen, nitrogen-oxygen mixture) and the flow rate (2000–6000 sccm). The results show that the surface electric field develops in three phases: establishment, maintenance, and dissipation. Both flow rate and oxygen content of the shielding gas significantly influence surface discharge behavior and the maximum electric field value. The analysis suggests that the establishment phase of the electric field results from charge transfer by ionization waves to the dielectric, while the maintenance of the electric field depends on pulse duration. During the dissipation phase, the positive surface charge attracts negatively charged species to the surface (electrons and negative ions), which causes charge neutralization at the surface. The oxygen content in the shielding gas impacts the electric field establishment phase, with a low oxygen content leading to lower photo-ionization rates and, consequently, surface discharges with branching. Shielding gas flow rates affect the amount of shielding gas mixed into the helium channel. Mixing less oxygen into the APPJ increases the electric field strength, as the ionization potential is lower than nitrogen. Excessive oxygen mixing traps more free electrons due to electronegativity, causing fewer ionized collisions and more negative ions in APPJ, ultimately lowering the electric field strength. This study shows that shielding gas type and flow rates can adjust surface charging, aiding in optimizing biomedical APPJ.
{"title":"Investigation of electric field distribution on dielectric exposed to DC-pulsed He plasma jet with shielding gas","authors":"Guoqiang Liu, Yang Xia, Kefeng Shang, Dongping Liu","doi":"10.1088/1361-6463/ad0060","DOIUrl":"https://doi.org/10.1088/1361-6463/ad0060","url":null,"abstract":"Abstract Atmospheric pressure plasma jets (APPJs) produce reactive species and electric fields for biomedical applications. Gas shields control plasma plume-surrounding gas interactions, regulating reactive species generation and electric field strength. However, the surface electric field distribution is still unclear and needs urgent attention. Here, the electric field distribution on the surface exposed to a helium APPJ with shielding gas is investigated using the Pockels technique. This study considers the influence of the type of shielding gas (ambient air, dry air, nitrogen, oxygen, nitrogen-oxygen mixture) and the flow rate (2000–6000 sccm). The results show that the surface electric field develops in three phases: establishment, maintenance, and dissipation. Both flow rate and oxygen content of the shielding gas significantly influence surface discharge behavior and the maximum electric field value. The analysis suggests that the establishment phase of the electric field results from charge transfer by ionization waves to the dielectric, while the maintenance of the electric field depends on pulse duration. During the dissipation phase, the positive surface charge attracts negatively charged species to the surface (electrons and negative ions), which causes charge neutralization at the surface. The oxygen content in the shielding gas impacts the electric field establishment phase, with a low oxygen content leading to lower photo-ionization rates and, consequently, surface discharges with branching. Shielding gas flow rates affect the amount of shielding gas mixed into the helium channel. Mixing less oxygen into the APPJ increases the electric field strength, as the ionization potential is lower than nitrogen. Excessive oxygen mixing traps more free electrons due to electronegativity, causing fewer ionized collisions and more negative ions in APPJ, ultimately lowering the electric field strength. This study shows that shielding gas type and flow rates can adjust surface charging, aiding in optimizing biomedical APPJ.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135923446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-12DOI: 10.1088/1361-6463/acf942
Ravi Patel, Rik Peelen, Jeroen van Oijen, Nico Dam, Sander Nijdam
Abstract This work aims to find how coupled energy per pulse influences the ability of a pulsed dielectric barrier discharge (DBD) plasma to ignite fuel-lean methane–air flow. For that, experiments are performed on a custom-built DBD flow reactor with a variable dielectric thickness and the discharge is operated by bursts of 10 ns duration pulses at 3 kHz repetition rate. With an increase in dielectric thickness, we observe that the coupled energy per pulse decreases even though applied voltage conditions are similar and so more pulses are required to ignite the lean mixture. Interestingly, we observe a significant increase in the minimum ignition energy ( MIE ) with an increase in the thickness beyond 3 mm. Moreover, the ignition kernel growth rate is much slower in the thicker dielectric cases even though total energy coupling per burst is similar. This phenomenon is investigated further by evaluating plasma parameters using electrical and optical diagnostics. Effective dielectric capacitance, discharge current, and voltage drop across the gas gap are derived from an equivalent circuit analysis, whereas plasma gas temperature and effective reduced electric field ( E/N ) are estimated from optical emission spectroscopy. From these analyses, we conclude that a thicker dielectric limits the discharge current and so the plasma filament temperature. For more than 3 mm thick dielectric cases, the filament heating per pulse is too low to achieve strong enough plasma pulse-to-pulse coupling which eventually leads to higher MIE and slower ignition kernel growth rate or the inability to ignite at all.
{"title":"How pulse energy affects ignition efficiency of DBD plasma assisted combustion","authors":"Ravi Patel, Rik Peelen, Jeroen van Oijen, Nico Dam, Sander Nijdam","doi":"10.1088/1361-6463/acf942","DOIUrl":"https://doi.org/10.1088/1361-6463/acf942","url":null,"abstract":"Abstract This work aims to find how coupled energy per pulse influences the ability of a pulsed dielectric barrier discharge (DBD) plasma to ignite fuel-lean methane–air flow. For that, experiments are performed on a custom-built DBD flow reactor with a variable dielectric thickness and the discharge is operated by bursts of 10 ns duration pulses at 3 kHz repetition rate. With an increase in dielectric thickness, we observe that the coupled energy per pulse decreases even though applied voltage conditions are similar and so more pulses are required to ignite the lean mixture. Interestingly, we observe a significant increase in the minimum ignition energy ( MIE ) with an increase in the thickness beyond 3 mm. Moreover, the ignition kernel growth rate is much slower in the thicker dielectric cases even though total energy coupling per burst is similar. This phenomenon is investigated further by evaluating plasma parameters using electrical and optical diagnostics. Effective dielectric capacitance, discharge current, and voltage drop across the gas gap are derived from an equivalent circuit analysis, whereas plasma gas temperature and effective reduced electric field ( <?CDATA $E/N$?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:mi>E</mml:mi> <mml:mrow> <mml:mo>/</mml:mo> </mml:mrow> <mml:mi>N</mml:mi> </mml:math> ) are estimated from optical emission spectroscopy. From these analyses, we conclude that a thicker dielectric limits the discharge current and so the plasma filament temperature. For more than 3 mm thick dielectric cases, the filament heating per pulse is too low to achieve strong enough plasma pulse-to-pulse coupling which eventually leads to higher MIE and slower ignition kernel growth rate or the inability to ignite at all.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135922849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Four samples containing magnetic iron oxide nanoparticles (MIONs) of various sizes are prepared employing a simple low-temperature method of oxidative precipitation from FeCl 2 ∙4H 2 O–NaOH–NaNO 3 aqueous solution. For the preparation of two samples, the usual oxidation-precipitation synthesis protocol is modified by using ethylenediaminetetraacetic acid (EDTA) chelating agent as a stabilizer of the Fe 2+ ions in a solution, which results in the partial capping of the prepared MIONs with EDTA molecules. Three out of four samples are subjected to citric acid (CA) functionalization in the post synthesis protocol. Structural and magnetic properties of the synthesized MIONs are assessed using various experimental techniques (XRD, TEM, Fourier transform infrared, dynamic light scattering, Mössbauer, and SQUID). The average size of spherical-like MIONs is tuned from 7 nm to 38 nm by changing the synthesis protocol. Their room temperature saturation magnetization, M s , is in the range of 43 to 91 emu g −1 . Magnetic heating ability, expressed via specific absorption rate value, which ranges from 139 to 390 W/g Fe , is discussed in relation to their structural and magnetic properties and the possible energy dissipation mechanisms involved. The best heating performance is exhibited by the sample decorated with EDTA and with a bimodal size distribution with average particle sizes of 14 and 37 nm and M s = 87 emu g −1 . Though this sample contains particles prone to form aggregates, capping with EDTA provides good colloidal stability of this sample, thus preserving the magnetic heating ability. It is demonstrated that two samples, consisting of 7 nm-sized CA- or 14 nm-sized EDTA/CA-functionalized superparamagnetic MIONs, with a similar hydrodynamic radius, heat in a very similar way in the relatively fast oscillating alternating current magnetic field, f = 577 kHz.
{"title":"CA and/or EDTA Functionalized Magnetic Iron Oxide Nanoparticles by Oxidative Precipitation from FeCl2 Solution: Structural and Magnetic Study","authors":"Mirjana Milić, Nataša Jović Orsini, Smilja Marković","doi":"10.1088/1361-6463/acff06","DOIUrl":"https://doi.org/10.1088/1361-6463/acff06","url":null,"abstract":"Abstract Four samples containing magnetic iron oxide nanoparticles (MIONs) of various sizes are prepared employing a simple low-temperature method of oxidative precipitation from FeCl 2 ∙4H 2 O–NaOH–NaNO 3 aqueous solution. For the preparation of two samples, the usual oxidation-precipitation synthesis protocol is modified by using ethylenediaminetetraacetic acid (EDTA) chelating agent as a stabilizer of the Fe 2+ ions in a solution, which results in the partial capping of the prepared MIONs with EDTA molecules. Three out of four samples are subjected to citric acid (CA) functionalization in the post synthesis protocol. Structural and magnetic properties of the synthesized MIONs are assessed using various experimental techniques (XRD, TEM, Fourier transform infrared, dynamic light scattering, Mössbauer, and SQUID). The average size of spherical-like MIONs is tuned from 7 nm to 38 nm by changing the synthesis protocol. Their room temperature saturation magnetization, M s , is in the range of 43 to 91 emu g −1 . Magnetic heating ability, expressed via specific absorption rate value, which ranges from 139 to 390 W/g Fe , is discussed in relation to their structural and magnetic properties and the possible energy dissipation mechanisms involved. The best heating performance is exhibited by the sample decorated with EDTA and with a bimodal size distribution with average particle sizes of 14 and 37 nm and M s = 87 emu g −1 . Though this sample contains particles prone to form aggregates, capping with EDTA provides good colloidal stability of this sample, thus preserving the magnetic heating ability. It is demonstrated that two samples, consisting of 7 nm-sized CA- or 14 nm-sized EDTA/CA-functionalized superparamagnetic MIONs, with a similar hydrodynamic radius, heat in a very similar way in the relatively fast oscillating alternating current magnetic field, f = 577 kHz.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135922871","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract We present the design of a H 2 gas sensor based on palladium (Pd) decorated silicon-on-insulator (SOI) nanowire field effect transistor (FET) with a standard SOI complementary metal-oxide-semiconductor fabrication process, where a top Pd layer plays a dual role of a catalyst and a surrounding metal gate. A numerical study was conducted based on a simplified steady-state model to describe the sensing mechanism of H 2 in dry air at 300 K. The simulation is based on the model of dissociative H 2 adsorption on the Pd surface and the formation of a dipole layer at the Pd/SiO 2 interface. The H atoms induced dipoles lead to a potential drop which exponentially increases the FET drain current and consequently, the sensor response. The FET drain current is controlled by its back-gate bias and by varying the H 2 concentrations; it is shown that the drain current response reaches 1.8 × 10 8 % for 0.8% H 2 in air and a superior sensitivity of 4.58 × 10 4 %/ppm in the sub-threshold operation regime. The sensor exhibits an outstanding theoretical detection limit of 50 ppt (response of 1%) and an upper dynamic range limit of 7000 ppm which allow for timely and accurate detection of H 2 gas presence. The power consumption ranges between ∼10 fW (dry air) to ∼20 nW (0.8% H 2 in dry air) and therefore paves the way for a very large-scale integration commercial sensing platform.
{"title":"Design and Modeling of the Electrostatically Controlled Nanowire FET for Ppt-level Hydrogen Sensing","authors":"Zoe Mutsafi, Klimentiy Shimanovich, Anwesha Mukherjee, Yossi Rosenwaks","doi":"10.1088/1361-6463/acffd7","DOIUrl":"https://doi.org/10.1088/1361-6463/acffd7","url":null,"abstract":"Abstract We present the design of a H 2 gas sensor based on palladium (Pd) decorated silicon-on-insulator (SOI) nanowire field effect transistor (FET) with a standard SOI complementary metal-oxide-semiconductor fabrication process, where a top Pd layer plays a dual role of a catalyst and a surrounding metal gate. A numerical study was conducted based on a simplified steady-state model to describe the sensing mechanism of H 2 in dry air at 300 K. The simulation is based on the model of dissociative H 2 adsorption on the Pd surface and the formation of a dipole layer at the Pd/SiO 2 interface. The H atoms induced dipoles lead to a potential drop which exponentially increases the FET drain current and consequently, the sensor response. The FET drain current is controlled by its back-gate bias and by varying the H 2 concentrations; it is shown that the drain current response reaches 1.8 × 10 8 % for 0.8% H 2 in air and a superior sensitivity of 4.58 × 10 4 %/ppm in the sub-threshold operation regime. The sensor exhibits an outstanding theoretical detection limit of 50 ppt (response of 1%) and an upper dynamic range limit of 7000 ppm which allow for timely and accurate detection of H 2 gas presence. The power consumption ranges between ∼10 fW (dry air) to ∼20 nW (0.8% H 2 in dry air) and therefore paves the way for a very large-scale integration commercial sensing platform.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135923445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract In an electronic (fermionic) system, these chiral edge states (CESs) allow inversely polarized carriers to propagate in opposite directions at the edge of the topological insulators, which is related to the time-reversal symmetry (TRS) in fermionic systems. However, in acoustic (bosonic) systems, unlike those exhibited by fermionic systems, since there is no inherent polarization, it is generally believed that the CESs protected by fermionic TRS with independent counter-propagating cannot be supported. Herein, a strategy that achieves the counter-propagating CESs in topological metamaterials with fermionic TRS is reported in a 3D acoustic system. First, we designed a Floquet evolution protocol to incorporate effective fermionic TRS. Furthermore, by utilizing metamaterials, we creatively employ two subwavelength structures, that is, a cavity structure for adjusting the phase shift and a tube structure for providing coupling, which allows the model to be miniaturized. Finally, our experiment verifies the effectiveness of our approach. Our research results enrich the knowledge of topological metamaterials in the field of topological physics and pave the way for exploring fermionic properties in bosonic systems.
{"title":"Observation of fermionic time-reversal symmetry in acoustic topological metamaterials","authors":"Yibao Dong, Jianbing Shi, Yuanbo Wang, Changlin Ding, Xiaopeng Zhao","doi":"10.1088/1361-6463/acff04","DOIUrl":"https://doi.org/10.1088/1361-6463/acff04","url":null,"abstract":"Abstract In an electronic (fermionic) system, these chiral edge states (CESs) allow inversely polarized carriers to propagate in opposite directions at the edge of the topological insulators, which is related to the time-reversal symmetry (TRS) in fermionic systems. However, in acoustic (bosonic) systems, unlike those exhibited by fermionic systems, since there is no inherent polarization, it is generally believed that the CESs protected by fermionic TRS with independent counter-propagating cannot be supported. Herein, a strategy that achieves the counter-propagating CESs in topological metamaterials with fermionic TRS is reported in a 3D acoustic system. First, we designed a Floquet evolution protocol to incorporate effective fermionic TRS. Furthermore, by utilizing metamaterials, we creatively employ two subwavelength structures, that is, a cavity structure for adjusting the phase shift and a tube structure for providing coupling, which allows the model to be miniaturized. Finally, our experiment verifies the effectiveness of our approach. Our research results enrich the knowledge of topological metamaterials in the field of topological physics and pave the way for exploring fermionic properties in bosonic systems.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135922866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-11DOI: 10.1088/1361-6463/acfc53
Aleksandr V Meshchanov, Aleksandr Shishpanov, Yury Z Ionikh
Abstract The effect of irradiation with visible spectrum light on breakdown in discharge tubes 75–80 cm long and 1.5 cm in inner diameter in rare gases at a pressure of ∼1 Torr was studied. A ramp voltage of variable slope in the range of ∼10 –1 –10 5 kV s −1 was applied to the tube anode. The tube was illuminated by radiation from fluorescent lamps operating in a continuous mode, as well as by LEDs or a laser diode operating in a pulsed mode. The breakdown voltage and the pre-breakdown ionization wave (IW) velocity were measured. Illumination led to a change in the breakdown potential. The sign of this change depended on the anode voltage rise rate d U/ d t . At d U/ d t > 10 2 –10 3 kV s −1 , the breakdown voltage decreased. A similar effect was observed earlier and was explained by the appearance of electrons in the discharge gap under the light action, as a result of which the breakdown delay time decreased. This, in turn, caused a decrease in the breakdown voltage. At d U/ d t < 10 1 –10 2 kV s −1 , on the contrary, the breakdown potential increased; at d U/ d t ∼ 0.1 kV s −1 , this increase could reach 5–6 times. The dependence of the observed effect on the radiation intensity, its wavelength, and the illuminated area position on the tube surface is studied. The pre-breakdown IW behaved in an unusual way under these conditions: its velocity and the signal amplitude recorded by the capacitive probe increased when moving from the high-voltage anode to the cathode. It is assumed that the observed features are caused by the desorption of weakly bound electrons from the tube wall surface under the action of irradiation. These electrons create a current that charges the wall near the anode. Since the first stage of discharge ignition is the initial breakdown between the anode and the tube wall, the anode potential for such a breakdown should increase, which means an increase in the breakdown voltage. Additional experiments with the initiation of a preliminary IW by a pulse applied to the cathode, confirmed the existence of a charge on the wall near the anode.
摘要:研究了可见光在压力为~ 1 Torr的稀有气体中长75 ~ 80 cm、内径1.5 cm的放电管照射对击穿的影响。在管阳极上施加范围为~ 10 -1 -10 5kv s−1的变斜率斜坡电压。该管由荧光灯在连续模式下的辐射照射，以及led或激光二极管在脉冲模式下的照射。测量了击穿电压和击穿前电离波速度。光照引起击穿电位的变化。这种变化的符号取决于阳极电压上升速率d U/ d t。在U/ d >10 2 ~ 10 3 kV s−1，击穿电压降低。先前也观察到类似的效应，并解释为在光作用下，在放电间隙中出现电子，导致击穿延迟时间减少。这反过来又导致了击穿电压的降低。At U/ d t <10 1 ~ 10 2 kV s−1，击穿电位反而增大;在d U/ d t ~ 0.1 kV s−1时，增加幅度可达5 ~ 6倍。研究了观测效应与辐射强度、波长和照射区域在管表面位置的关系。在这些条件下，预击穿电流表现出一种不寻常的方式:当从高压阳极移动到阴极时，其速度和电容探头记录的信号幅度增加。假设所观察到的特征是在辐照作用下弱束缚电子从管壁表面解吸引起的。这些电子产生电流，给阳极附近的壁充电。由于放电点火的第一阶段是阳极和管壁之间的初始击穿，因此这种击穿的阳极电位应该增加，这意味着击穿电压的增加。在阴极上施加脉冲引发初步IW的附加实验，证实了阳极附近壁上电荷的存在。
{"title":"Hindering breakdown in a long discharge tube by visible spectrum light illumination","authors":"Aleksandr V Meshchanov, Aleksandr Shishpanov, Yury Z Ionikh","doi":"10.1088/1361-6463/acfc53","DOIUrl":"https://doi.org/10.1088/1361-6463/acfc53","url":null,"abstract":"Abstract The effect of irradiation with visible spectrum light on breakdown in discharge tubes 75–80 cm long and 1.5 cm in inner diameter in rare gases at a pressure of ∼1 Torr was studied. A ramp voltage of variable slope in the range of ∼10 –1 –10 5 kV s −1 was applied to the tube anode. The tube was illuminated by radiation from fluorescent lamps operating in a continuous mode, as well as by LEDs or a laser diode operating in a pulsed mode. The breakdown voltage and the pre-breakdown ionization wave (IW) velocity were measured. Illumination led to a change in the breakdown potential. The sign of this change depended on the anode voltage rise rate d U/ d t . At d U/ d t > 10 2 –10 3 kV s −1 , the breakdown voltage decreased. A similar effect was observed earlier and was explained by the appearance of electrons in the discharge gap under the light action, as a result of which the breakdown delay time decreased. This, in turn, caused a decrease in the breakdown voltage. At d U/ d t < 10 1 –10 2 kV s −1 , on the contrary, the breakdown potential increased; at d U/ d t ∼ 0.1 kV s −1 , this increase could reach 5–6 times. The dependence of the observed effect on the radiation intensity, its wavelength, and the illuminated area position on the tube surface is studied. The pre-breakdown IW behaved in an unusual way under these conditions: its velocity and the signal amplitude recorded by the capacitive probe increased when moving from the high-voltage anode to the cathode. It is assumed that the observed features are caused by the desorption of weakly bound electrons from the tube wall surface under the action of irradiation. These electrons create a current that charges the wall near the anode. Since the first stage of discharge ignition is the initial breakdown between the anode and the tube wall, the anode potential for such a breakdown should increase, which means an increase in the breakdown voltage. Additional experiments with the initiation of a preliminary IW by a pulse applied to the cathode, confirmed the existence of a charge on the wall near the anode.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136057632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-11DOI: 10.1088/1361-6463/acff03
Xin Li, Ze-tong Li, Ling-Ling Wang, Qi Lin
Abstract We propose a nonreciprocal borophene metamaterial consisting of a longitudinally separated array of double-layer borophene nanoribbons (BNRs) suspended in the air, exhibiting the unidirectional reflectionless properties at exceptional points (EPs) in the near-infrared communication band. Based on the coupled mode theory and the transfer matrix method, the transmission characteristics of light in the proposed structure can be effectively described. The internal loss and radioactive loss factors of the plasmonic system are successfully calculated by employing the theoretical model we proposed. Thus we conduct the analytical description of the unidirectional reflectionless phenomenon between two borophene plasmonic resonators, where the analytical results show excellent consistency with the finite-difference time-domain simulations. Different from the waveguide structure, the proposed structure has better adjustability that the regulation of EPs can be dynamically achieved by manipulating carrier density and the spatial separation between double-layer of BNRs. Our research results possess the possibility for promising application in tunable nanoelectronic devices in the communication band.
{"title":"Unidirectional reflectionless propagation in borophene plasmonic metamaterials","authors":"Xin Li, Ze-tong Li, Ling-Ling Wang, Qi Lin","doi":"10.1088/1361-6463/acff03","DOIUrl":"https://doi.org/10.1088/1361-6463/acff03","url":null,"abstract":"Abstract We propose a nonreciprocal borophene metamaterial consisting of a longitudinally separated array of double-layer borophene nanoribbons (BNRs) suspended in the air, exhibiting the unidirectional reflectionless properties at exceptional points (EPs) in the near-infrared communication band. Based on the coupled mode theory and the transfer matrix method, the transmission characteristics of light in the proposed structure can be effectively described. The internal loss and radioactive loss factors of the plasmonic system are successfully calculated by employing the theoretical model we proposed. Thus we conduct the analytical description of the unidirectional reflectionless phenomenon between two borophene plasmonic resonators, where the analytical results show excellent consistency with the finite-difference time-domain simulations. Different from the waveguide structure, the proposed structure has better adjustability that the regulation of EPs can be dynamically achieved by manipulating carrier density and the spatial separation between double-layer of BNRs. Our research results possess the possibility for promising application in tunable nanoelectronic devices in the communication band.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136057968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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