Purpose-Association of American railroads(AAR)standard automatic couplers are designed for much higher capacity than the normal operating loads.However,failure of knuckles and coupler bodies is still a common occurren...Purpose-Association of American railroads(AAR)standard automatic couplers are designed for much higher capacity than the normal operating loads.However,failure of knuckles and coupler bodies is still a common occurrence.Recent studies have shown that fatigue is the main reason behind such failures below the expected load.Moreover,knuckle failures occur more frequently than coupler body failures,which cause operational disruptions and also influence overall coupler life because of nonconforming contact between a new knuckle and an old coupler.In addition to new and old counterparts,undesired contact conditions are often the case with the new assembly due to casting-based manufacturing inaccuracies.Design/methodology/approach-A study is thus carried out in this paper to understand the variation of load transfer paths and its consequences caused by dimensional variability.A finite element model of an E-type coupler’s knuckle is developed and different possible contact conditions of the knuckle with the coupler head are simulated.Knuckles generally fail in pulling mode,during which the possible contacting elements of knuckle are pulling lugs,pin protector regions and pinholes.Due to dimensional variability,contact conditions may exist where an individual or a combination of these elements are in contact.Findings-Simulation results indicate that under regular operational conditions,having only the pulling lugs in contact reduces the risk of knuckle failure and maintains assembly integrity even if the knuckle fails.However,under extreme loading conditions,the safest scenario is when both pulling lugs and pin protector regions are in contact.Originality/value-These findings are believed to assist in defining the dimensional variability limits to ensure the desired contacts between the mating surfaces of the knuckle and coupler body of railway couplers of AAR type.This work contributes to understanding implications of dimensional variability in the railway couplers.The insight presented are useful in design,manufacturing and maintenance of railway coupler’s knuckle.展开更多
In recent years,the use of deep learning to replace traditional numerical methods for electromagnetic propagation has shown tremendous potential in the rapid design of photonic devices.However,most research on deep le...In recent years,the use of deep learning to replace traditional numerical methods for electromagnetic propagation has shown tremendous potential in the rapid design of photonic devices.However,most research on deep learning has focused on single-layer grating couplers,and the accuracy of multi-layer grating couplers has not yet reached a high level.This paper proposes and demonstrates a novel deep learning network-assisted strategy for inverse design.The network model is based on a multi-layer perceptron(MLP)and incorporates convolutional neural networks(CNNs)and transformers.Through the stacking of multiple layers,it achieves a high-precision design for both multi-layer and single-layer raster couplers with various functionalities.The deep learning network exhibits exceptionally high predictive accuracy,with an average absolute error across the full wavelength range of 1300–1700 nm being only 0.17%,and an even lower predictive absolute error below 0.09%at the specific wavelength of 1550 nm.By combining the deep learning network with the genetic algorithm,we can efficiently design grating couplers that perform different functions.Simulation results indicate that the designed single-wavelength grating couplers achieve coupling efficiencies exceeding 80%at central wavelengths of 1550 nm and 1310 nm.The performance of designed dual-wavelength and broadband grating couplers also reaches high industry standards.Furthermore,the network structure and inverse design method are highly scalable and can be applied not only to multi-layer grating couplers but also directly to the prediction and design of single-layer grating couplers,providing a new perspective for the innovative development of photonic devices.展开更多
3-dB couplers are key building blocks for on-chip optical switches,optical phased arrays,and photonic computing applications,for the ease of realizing balanced beam splitting and combining.Adiabatic3-dB couplers ensur...3-dB couplers are key building blocks for on-chip optical switches,optical phased arrays,and photonic computing applications,for the ease of realizing balanced beam splitting and combining.Adiabatic3-dB couplers ensure exclusive excitation and propagation of the fundamental eigenmode along the waveguide,characterized by low insertion loss,broad bandwidth,low power imbalance,and resilience to fabrication variations.However,conventional adiabatic designs need to extend the propagation length to achieve broadband performance.In this paper,we overcome such a length-bandwidth trade-off by employing fast quasi-adiabatic(FAQUAD)dynamics in the TFLN 3-dB couplers,thereby accelerating the mode evolution process.Theoretical analysis predicts that the proposed 2×2 FAQUAD 3-dB coupler exhibits an unprecedented operation bandwidth of 350 nm(1285 to 1635 nm)with a FAQUAD taper length of only 88.9μm.Experimental characterization of the fabricated device demonstrates broadband 3-dB power splitting over 165 nm(exceeding the range of the used tunable laser:1470 to 1635 nm),achieving the power imbalance of<0.5 dB and insertion loss of 0.14 dB.Those results establish the foundation for next-generation photonic integrated circuits featuring high efficiency,compact footprint,and ultra-wide bandwidth.展开更多
With rapid advancements in physics and particle medicine,the domestic accelerator industry has grown rapidly.During the 12th Five-Year Plan period,the Institute of Modern Physics of the Chinese Academy of Sciences too...With rapid advancements in physics and particle medicine,the domestic accelerator industry has grown rapidly.During the 12th Five-Year Plan period,the Institute of Modern Physics of the Chinese Academy of Sciences took on a plurality of accelerator projects.Nevertheless,the stability of the coupler,a crucial system within the cavities of accelerators,has encountered certain difficulties.The alumina ceramics,which constitute the core component of the coupler,are increasingly prone to breakage and solder joint failures due to their inferior environmental adaptability,inadequate mechanical properties,and high gas emissions.Conversely,with the advancements in medical technology and materials science,zirconia ceramics have emerged as a prospective remedy for these problems.This type of ceramic is highly esteemed for its outstanding environmental adaptability,remarkable mechanical properties,and excellent high-temperature resistance,exhibiting extraordinary value in dental applications.This study investigates the use of zirconia ceramics in a 162.5 MHz 3-1/8"standard ceramic window,combining experimental data with finite element RF simulations and multi-physics analysis.A new coupler featuring a zirconia ceramic window was tested on a Quarter-Wave Resonator,demonstrating excellent alignment between electromagnetic simulations and measurement results.This reveals the substantial application potential and practical worth of the zirconia ceramic material in the context of accelerators.展开更多
This paper presents a novel approach to design a compact circular rat-race coupler with an ultrawide stopband, with the aim to reduce its size while maintaining performance. The design methodology begins with a common...This paper presents a novel approach to design a compact circular rat-race coupler with an ultrawide stopband, with the aim to reduce its size while maintaining performance. The design methodology begins with a common miniaturization technique to replace the conventional quarter-wavelength transmission line with an equivalent low-pass filter loaded with parallel coupled line and radial stubs. Since the latter leads to produce higher order harmonics, parasitic open-ended stubs are then properly introduced in the structure not only to overcome the issue but also to produce controllable transmission zeros. A versatile analytical model is also developed taking into account manufacturing restrictions, which makes it possible to extract the physical parameters of the coupler unit-cell for a given desired compactness percentage with respect to the conventional rat-race coupler. A prototype is fabricated and measured to validate the design,demonstrating the predicted behavior fairly achieved by numerical analysis. A significant size reduction of about 86.1% was achieved compared to the conventional design, while effectively suppressing higher order modes up to 23.4 GHz(including the 13th harmonic based on |S11|>-5 dB and |S21|<-17 dB)with high isolation level(|S41|<-17 dB) between the ports.展开更多
Fabrication-friendly superconducting qubits continue to be a leading candidate for scalable quantum computing.Recent developments in tunable couplers have significantly advanced the progress toward practical quantum p...Fabrication-friendly superconducting qubits continue to be a leading candidate for scalable quantum computing.Recent developments in tunable couplers have significantly advanced the progress toward practical quantum processors.However,high-performance quantum control,particularly two-qubit gates,depends on the delicate tuning of the coupler spectrum,as misalignment can lead to undesirable phenomena such as frequency crowding,which may cause errors including state leakage.Here,we propose an efficient method for characterizing the coupler spectrum through sideband drivings,obviating the need for additional components in current quantum processors.We demonstrate this technique experimentally by employing both continuous-wave and pulsed measurement protocols,successfully extracting the coupler spectrum.Furthermore,by utilizing the measured coupler spectrum,we calibrate the frequency dependence of the effective coupling strength between two qubits linked by the coupler.The proposed approach offers significant practical benefits,enabling the efficient characterization of the coupler spectrum in existing quantum architectures,thus paving the way for enhanced quantum control and scalability.展开更多
We propose an effective surface plasmon resonance system designed to achieve both negative and positive Goos–H??nchen shifts in reflected light.This system comprises a metal film and an underlying medium,where the re...We propose an effective surface plasmon resonance system designed to achieve both negative and positive Goos–H??nchen shifts in reflected light.This system comprises a metal film and an underlying medium,where the real part of the permittivity of the underlying medium must be less than unity.Surface plasmon polaritons can be excited at the lower surface of the metal when light is incident from the air onto the upper surface of the metal.The excitation of surface plasmon polaritons leads to the exploration of the Goos–H??nchen shift(G–HS).Control over the negative and positive(G–HS)is investigated via the wavelength of the incident light.The magnitude of the G–HS is strongly dependent on the incident wavelength.A remarkable enhancement of both negative and positive G–HS in the reflected light is achieved at certain wavelengths and incident angles.Our system paves the way for exploring different characteristics of optical switching and micro-sensors with very high precision.展开更多
Edge couplers,widely recognized for their efficiency and broad bandwidth,have gained significant attention as optical fiber-to-chip couplers.Silicon waveguides exhibit strong birefringence properties,resulting in subs...Edge couplers,widely recognized for their efficiency and broad bandwidth,have gained significant attention as optical fiber-to-chip couplers.Silicon waveguides exhibit strong birefringence properties,resulting in substantial polarization-dependent loss for edge couplers in the O-band.We introduce a bilayer and double-tip edge coupler designed to efficiently couple both transverse electric(TE)and transverse magnetic(TM)modes while maintaining compatibility with standard manufacturing processes used in commercial silicon photonics foundries.We have successfully designed and fabricated this edge coupler,achieving coupling losses of<1.52 dB∕facet for TE mode and 2 dB∕facet for TM mode when coupled with a lensed optical fiber[4-μmmode field diameter(MFD)]within the wavelength range of 1260 to 1360 nm.展开更多
We proposed and demonstrated the ultra-compact 1310/1550 nm wavelength multiplexer/demultiplexer assisted by subwavelength grating(SWG)using particle swarm optimization(PSO)algorithm in silicon-on-insulator(SOI)platfo...We proposed and demonstrated the ultra-compact 1310/1550 nm wavelength multiplexer/demultiplexer assisted by subwavelength grating(SWG)using particle swarm optimization(PSO)algorithm in silicon-on-insulator(SOI)platform.Through the self-imaging effect of multimode interference(MMI)coupler,the demultiplexing function for 1310 nm and 1550 nm wavelengths is implemented.After that,three parallel SWG-based slots are inserted into the MMI section so that the effective refractive index of the modes can be engineered and thus the beat length can be adjusted.Importantly,these three SWG slots significantly reduce the length of the device,which is much shorter than the length of traditional MMI-based wavelength demultiplexers.Ultimately,by using the PSO algorithm,the equivalent refractive index and width of the SWG in a certain range are optimized to achieve the best performance of the wavelength demultiplexer.It has been verified that the device footprint is only 2×30.68μm^(2),and 1 dB bandwidths of larger than 120 nm are acquired at 1310 nm and 1550 nm wavelengths.Meanwhile,the transmitted spectrum shows that the insertion loss(IL)values are below 0.47 dB at both wavelengths when the extinction ratio(ER)values are above 12.65 dB.This inverse design approach has been proved to be efficient in increasing bandwidth and reducing device length.展开更多
An ultracompact 3 dB coupler is designed and fabricated in silicon on insulator,based on 1×2 line tapered multimode interference (MMI) coupler.Comparing with the conventional straight MMI coupler,the device is...An ultracompact 3 dB coupler is designed and fabricated in silicon on insulator,based on 1×2 line tapered multimode interference (MMI) coupler.Comparing with the conventional straight MMI coupler,the device is ～40% shorter in length.The device exhibits uniformity of 1 3dB and excess loss of 2 5dB.展开更多
文摘Purpose-Association of American railroads(AAR)standard automatic couplers are designed for much higher capacity than the normal operating loads.However,failure of knuckles and coupler bodies is still a common occurrence.Recent studies have shown that fatigue is the main reason behind such failures below the expected load.Moreover,knuckle failures occur more frequently than coupler body failures,which cause operational disruptions and also influence overall coupler life because of nonconforming contact between a new knuckle and an old coupler.In addition to new and old counterparts,undesired contact conditions are often the case with the new assembly due to casting-based manufacturing inaccuracies.Design/methodology/approach-A study is thus carried out in this paper to understand the variation of load transfer paths and its consequences caused by dimensional variability.A finite element model of an E-type coupler’s knuckle is developed and different possible contact conditions of the knuckle with the coupler head are simulated.Knuckles generally fail in pulling mode,during which the possible contacting elements of knuckle are pulling lugs,pin protector regions and pinholes.Due to dimensional variability,contact conditions may exist where an individual or a combination of these elements are in contact.Findings-Simulation results indicate that under regular operational conditions,having only the pulling lugs in contact reduces the risk of knuckle failure and maintains assembly integrity even if the knuckle fails.However,under extreme loading conditions,the safest scenario is when both pulling lugs and pin protector regions are in contact.Originality/value-These findings are believed to assist in defining the dimensional variability limits to ensure the desired contacts between the mating surfaces of the knuckle and coupler body of railway couplers of AAR type.This work contributes to understanding implications of dimensional variability in the railway couplers.The insight presented are useful in design,manufacturing and maintenance of railway coupler’s knuckle.
基金sponsored by the National Key Scientific Instrument and Equipment Development Projects of China(Grant No.62027823)the National Natural Science Foun-dation of China(Grant No.61775048).
文摘In recent years,the use of deep learning to replace traditional numerical methods for electromagnetic propagation has shown tremendous potential in the rapid design of photonic devices.However,most research on deep learning has focused on single-layer grating couplers,and the accuracy of multi-layer grating couplers has not yet reached a high level.This paper proposes and demonstrates a novel deep learning network-assisted strategy for inverse design.The network model is based on a multi-layer perceptron(MLP)and incorporates convolutional neural networks(CNNs)and transformers.Through the stacking of multiple layers,it achieves a high-precision design for both multi-layer and single-layer raster couplers with various functionalities.The deep learning network exhibits exceptionally high predictive accuracy,with an average absolute error across the full wavelength range of 1300–1700 nm being only 0.17%,and an even lower predictive absolute error below 0.09%at the specific wavelength of 1550 nm.By combining the deep learning network with the genetic algorithm,we can efficiently design grating couplers that perform different functions.Simulation results indicate that the designed single-wavelength grating couplers achieve coupling efficiencies exceeding 80%at central wavelengths of 1550 nm and 1310 nm.The performance of designed dual-wavelength and broadband grating couplers also reaches high industry standards.Furthermore,the network structure and inverse design method are highly scalable and can be applied not only to multi-layer grating couplers but also directly to the prediction and design of single-layer grating couplers,providing a new perspective for the innovative development of photonic devices.
基金supported by the National Key Research and Development Program of China(Grant No.2024YFB2807903)the National Natural Science Foundation of China(Grant Nos.62025502 and 62475050)the Guangdong Introducing Innovative and Entrepreneurial Teams of“The Pearl River Talent Recruitment Program”(Grant No.2021ZT09X044)。
文摘3-dB couplers are key building blocks for on-chip optical switches,optical phased arrays,and photonic computing applications,for the ease of realizing balanced beam splitting and combining.Adiabatic3-dB couplers ensure exclusive excitation and propagation of the fundamental eigenmode along the waveguide,characterized by low insertion loss,broad bandwidth,low power imbalance,and resilience to fabrication variations.However,conventional adiabatic designs need to extend the propagation length to achieve broadband performance.In this paper,we overcome such a length-bandwidth trade-off by employing fast quasi-adiabatic(FAQUAD)dynamics in the TFLN 3-dB couplers,thereby accelerating the mode evolution process.Theoretical analysis predicts that the proposed 2×2 FAQUAD 3-dB coupler exhibits an unprecedented operation bandwidth of 350 nm(1285 to 1635 nm)with a FAQUAD taper length of only 88.9μm.Experimental characterization of the fabricated device demonstrates broadband 3-dB power splitting over 165 nm(exceeding the range of the used tunable laser:1470 to 1635 nm),achieving the power imbalance of<0.5 dB and insertion loss of 0.14 dB.Those results establish the foundation for next-generation photonic integrated circuits featuring high efficiency,compact footprint,and ultra-wide bandwidth.
文摘With rapid advancements in physics and particle medicine,the domestic accelerator industry has grown rapidly.During the 12th Five-Year Plan period,the Institute of Modern Physics of the Chinese Academy of Sciences took on a plurality of accelerator projects.Nevertheless,the stability of the coupler,a crucial system within the cavities of accelerators,has encountered certain difficulties.The alumina ceramics,which constitute the core component of the coupler,are increasingly prone to breakage and solder joint failures due to their inferior environmental adaptability,inadequate mechanical properties,and high gas emissions.Conversely,with the advancements in medical technology and materials science,zirconia ceramics have emerged as a prospective remedy for these problems.This type of ceramic is highly esteemed for its outstanding environmental adaptability,remarkable mechanical properties,and excellent high-temperature resistance,exhibiting extraordinary value in dental applications.This study investigates the use of zirconia ceramics in a 162.5 MHz 3-1/8"standard ceramic window,combining experimental data with finite element RF simulations and multi-physics analysis.A new coupler featuring a zirconia ceramic window was tested on a Quarter-Wave Resonator,demonstrating excellent alignment between electromagnetic simulations and measurement results.This reveals the substantial application potential and practical worth of the zirconia ceramic material in the context of accelerators.
文摘This paper presents a novel approach to design a compact circular rat-race coupler with an ultrawide stopband, with the aim to reduce its size while maintaining performance. The design methodology begins with a common miniaturization technique to replace the conventional quarter-wavelength transmission line with an equivalent low-pass filter loaded with parallel coupled line and radial stubs. Since the latter leads to produce higher order harmonics, parasitic open-ended stubs are then properly introduced in the structure not only to overcome the issue but also to produce controllable transmission zeros. A versatile analytical model is also developed taking into account manufacturing restrictions, which makes it possible to extract the physical parameters of the coupler unit-cell for a given desired compactness percentage with respect to the conventional rat-race coupler. A prototype is fabricated and measured to validate the design,demonstrating the predicted behavior fairly achieved by numerical analysis. A significant size reduction of about 86.1% was achieved compared to the conventional design, while effectively suppressing higher order modes up to 23.4 GHz(including the 13th harmonic based on |S11|>-5 dB and |S21|<-17 dB)with high isolation level(|S41|<-17 dB) between the ports.
基金supported by the Innovation Program for Quantum Science and Technology(Grant Nos.2021ZD0301702 and 2024ZD0302000)the Natural Science Foundation of of Jiangsu Province(Grant No.BK20232002)+2 种基金the National Natural Science Foundation of China(Grant Nos.U21A20436 and 12074179)the Natural Science Foundation of Shandong Province(Grant No.ZR2023LZH002)Nanjing University-China Mobile Communications Group Co.,Ltd.Joint Institute.
文摘Fabrication-friendly superconducting qubits continue to be a leading candidate for scalable quantum computing.Recent developments in tunable couplers have significantly advanced the progress toward practical quantum processors.However,high-performance quantum control,particularly two-qubit gates,depends on the delicate tuning of the coupler spectrum,as misalignment can lead to undesirable phenomena such as frequency crowding,which may cause errors including state leakage.Here,we propose an efficient method for characterizing the coupler spectrum through sideband drivings,obviating the need for additional components in current quantum processors.We demonstrate this technique experimentally by employing both continuous-wave and pulsed measurement protocols,successfully extracting the coupler spectrum.Furthermore,by utilizing the measured coupler spectrum,we calibrate the frequency dependence of the effective coupling strength between two qubits linked by the coupler.The proposed approach offers significant practical benefits,enabling the efficient characterization of the coupler spectrum in existing quantum architectures,thus paving the way for enhanced quantum control and scalability.
基金Hubei University of Automotive Technology through the start-up research grant(BK202212),located in Shiyan 442002,China。
文摘We propose an effective surface plasmon resonance system designed to achieve both negative and positive Goos–H??nchen shifts in reflected light.This system comprises a metal film and an underlying medium,where the real part of the permittivity of the underlying medium must be less than unity.Surface plasmon polaritons can be excited at the lower surface of the metal when light is incident from the air onto the upper surface of the metal.The excitation of surface plasmon polaritons leads to the exploration of the Goos–H??nchen shift(G–HS).Control over the negative and positive(G–HS)is investigated via the wavelength of the incident light.The magnitude of the G–HS is strongly dependent on the incident wavelength.A remarkable enhancement of both negative and positive G–HS in the reflected light is achieved at certain wavelengths and incident angles.Our system paves the way for exploring different characteristics of optical switching and micro-sensors with very high precision.
基金supported by the National Key R&D Program of China(Grant No.2023YFB2806600)the National Natural Science Foundation of China(Grant Nos.62125503,62261160388,and 62105115)+4 种基金the Natural Science Foundation of Hubei Province of China(Grant No.2023AFA028)the Major Program(JD)of Hubei Province(Grant No.2023BAA012)the High Quality Development Special Project of the Ministry of Industry and Information Technology,the Key Research and Development Program of Hubei Province(Grant No.2021BAA004)the Open Project Program of SJTU-Pinghu Institute of Intelligent Optoelectronics(Grant No.2022SPIOE102)the Innovation Project of Optics Valley Laboratory(Grant No.OVL2023ZD004).
文摘Edge couplers,widely recognized for their efficiency and broad bandwidth,have gained significant attention as optical fiber-to-chip couplers.Silicon waveguides exhibit strong birefringence properties,resulting in substantial polarization-dependent loss for edge couplers in the O-band.We introduce a bilayer and double-tip edge coupler designed to efficiently couple both transverse electric(TE)and transverse magnetic(TM)modes while maintaining compatibility with standard manufacturing processes used in commercial silicon photonics foundries.We have successfully designed and fabricated this edge coupler,achieving coupling losses of<1.52 dB∕facet for TE mode and 2 dB∕facet for TM mode when coupled with a lensed optical fiber[4-μmmode field diameter(MFD)]within the wavelength range of 1260 to 1360 nm.
基金supported by the National Natural Science Foundation of China(No.61505160)the Innovation Capability Support Program of Shaanxi(No.2018KJXX-042)+2 种基金the Natural Science Basic Research Program of Shaanxi(No.2019JM-084)the State Key Laboratory of Transient Optics and Photonics(No.SKLST202108)the Graduate Innovation and Practical Ability Training Project of Xi’an Shiyou University(No.YCS22213190)。
文摘We proposed and demonstrated the ultra-compact 1310/1550 nm wavelength multiplexer/demultiplexer assisted by subwavelength grating(SWG)using particle swarm optimization(PSO)algorithm in silicon-on-insulator(SOI)platform.Through the self-imaging effect of multimode interference(MMI)coupler,the demultiplexing function for 1310 nm and 1550 nm wavelengths is implemented.After that,three parallel SWG-based slots are inserted into the MMI section so that the effective refractive index of the modes can be engineered and thus the beat length can be adjusted.Importantly,these three SWG slots significantly reduce the length of the device,which is much shorter than the length of traditional MMI-based wavelength demultiplexers.Ultimately,by using the PSO algorithm,the equivalent refractive index and width of the SWG in a certain range are optimized to achieve the best performance of the wavelength demultiplexer.It has been verified that the device footprint is only 2×30.68μm^(2),and 1 dB bandwidths of larger than 120 nm are acquired at 1310 nm and 1550 nm wavelengths.Meanwhile,the transmitted spectrum shows that the insertion loss(IL)values are below 0.47 dB at both wavelengths when the extinction ratio(ER)values are above 12.65 dB.This inverse design approach has been proved to be efficient in increasing bandwidth and reducing device length.
文摘An ultracompact 3 dB coupler is designed and fabricated in silicon on insulator,based on 1×2 line tapered multimode interference (MMI) coupler.Comparing with the conventional straight MMI coupler,the device is ～40% shorter in length.The device exhibits uniformity of 1 3dB and excess loss of 2 5dB.
