An ultrawideband reflectionless metamaterial absorber(MA)is proposed by replacing the metallic ground with the complementary split-ring resonator(CSRR)structure.The proposed MA exhibits-10 d B reflectivity spectrum fr...An ultrawideband reflectionless metamaterial absorber(MA)is proposed by replacing the metallic ground with the complementary split-ring resonator(CSRR)structure.The proposed MA exhibits-10 d B reflectivity spectrum from 1 GHz to 20 GHz,which maintains more than 90%absorption from 1.5 GHz to20 GHz.Furthermore,it achieves angle stability for TE and TM polarization at oblique incident angles up to 40°and 65°,respectively.To achieve broadband absorption spectrum,we have adopted a single-layer high-impedance surface(HIS)loaded with a double-layer magnetic material(MM)structure.To further realize the RCS reduction into a lower frequency range,we have employed the scattering cancellation technology into the traditional metallic ground.Finally,we have fabricated a sample exhibiting the 10 d B RCS reduction from 1 GHz to 20 GHz with a thickness of 10 mm.Measurement and simulation results confirm that the proposed MA exhibits excellent comprehensive performance,making it suitable for many practical applications.展开更多
The field of terahertz devices is important in terahertz technology.However,most of the current devices have limited functionality and poor performance.To improve device performance and achieve multifunctionality,we d...The field of terahertz devices is important in terahertz technology.However,most of the current devices have limited functionality and poor performance.To improve device performance and achieve multifunctionality,we designed a terahertz device based on a combination of VO_(2)and metamaterials.This device can be tuned using the phase-transition characteristics of VO_(2),which is included in the triple-layer structure of the device,along with SiO_(2)and Au.The terahertz device exhibits various advantageous features,including broadband coverage,high absorption capability,dynamic tunability,simple structural design,polarization insensitivity,and incidentangle insensitivity.The simulation results showed that by controlling the temperature,the terahertz device achieved a thermal modulation range of spectral absorption from 0 to 0.99.At 313 K,the device exhibited complete reflection of terahertz waves.As the temperature increased,the absorption rate also increased.When the temperature reached 353 K,the device absorption rate exceeded 97.7%in the range of 5-8.55 THz.This study used the effective medium theory to elucidate the correlation between conductivity and temperature during the phase transition of VO_(2).Simultaneously,the variation in device performance was further elucidated by analyzing and depicting the intensity distribution of the electric field on the device surface at different temperatures.Furthermore,the impact of various structural parameters on device performance was examined,offering valuable insights and suggestions for selecting suitable parameter values in real-world applications.These characteristics render the device highly promising for applications in stealth technology,energy harvesting,modulation,and other related fields,thus showcasing its significant potential.展开更多
In the field of short-range optical interconnects,the development of low-power-consumption,ultrawideband on-chip optical waveguide amplifiers is of critical importance.Central to this advancement is the creation of ho...In the field of short-range optical interconnects,the development of low-power-consumption,ultrawideband on-chip optical waveguide amplifiers is of critical importance.Central to this advancement is the creation of host materials that require low pump power and provide ultrabroadband emission capabilities.We introduce a tri-doped lanthanum aluminate glass(composition:5Er_(2)O_(3)-5Yb_(2)O_(3)-0.2Tm_(2)O_(3)-43.8La_(2)O_(3)-46Al_(2)O_(3)),which exhibits exceptional near-infrared(NIR)luminescence intensity,significantly outperforming other bands by 3 orders of magnitude.This glass can achieve an ultrawideband NIR gain spanning 478 nm,from 1510 to 1988 nm.Notably,the glass achieves positive optical gain with a low population inversion threshold(P>0.2),highlighting its efficiency and low-power consumption.The high glass transition temperature(Tg∼842°C)and large temperature difference(ΔT∼120°C)between Tg and the onset of crystallization(Tx)indicate excellent thermal stability,which is crucial for producing high-quality amorphous films for on-chip amplifiers.This research examines the unique energy levels and spectral properties of the Er^(3+)-Yb^(3+)-Tm^(3+) tri-doped glass,assessing its potential for use in ultrawideband on-chip optical waveguide amplifiers.This work lays the groundwork for low-power,ultrabroadband on-chip waveguide amplifiers,offering new avenues for short-range optical interconnect systems.展开更多
A new design of ultrawideband(UWB) antenna of coplanar waveguide(CPW)-fed is proposed. The antenna is composed of a cross-shaped patch and house-shaped slot with the minimum dimension of 21 mm ×20 mm × 1.6 m...A new design of ultrawideband(UWB) antenna of coplanar waveguide(CPW)-fed is proposed. The antenna is composed of a cross-shaped patch and house-shaped slot with the minimum dimension of 21 mm ×20 mm × 1.6 mm. The analysis of S11, VSWR, radiation pattern and surface current is discussed with HFSS simulation software, and also the effect of parameters is presented. Experimental results show that the bandwidth of the antenna covers 110.67%(3.3—11.6 GHz) of UWB range with return loss better than 10 dB. And the good impedance matching in frequency band confirms the antenna is a good candidate for the application of wireless system.展开更多
Low frequency ultrawideband (LF UWB) synthetic aperture radar (SAR) has lately become of a particular interest to SAR community. Monostatic and bistatic LF UWB SAR system has the well foliage penetrating capability, h...Low frequency ultrawideband (LF UWB) synthetic aperture radar (SAR) has lately become of a particular interest to SAR community. Monostatic and bistatic LF UWB SAR system has the well foliage penetrating capability, high-resolution imaging and providing the increased information. In 2015, a monostatic and bistatic LF UWB SAR imaging experiment was conducted. In this experiment, the monostatic and bistatic data were collected simultaneously by operating a moving vehicle-based radar in the SAR mode, in conjunction with a stationary ground-based receiver. The aim was to investigate the imaging property of the bistatic LF UWB SAR system. The one pulse per second (1 PPS) signal in combination with the global position system (GPS) disciplined 100 MHz oscillator from the GPS receivers was used to implement the time and frequency synchronization in this SAR system. The bistatic SAR image was obtained by the subaperture spectrum-equilibrium method integrated with the fast factorized back projection (FFBP) algorithm. Bistatic experiment results are show to prove the validity of the bistatic LF UWB SAR imaging experiment.展开更多
Investigations are directed to the development of high-power sources ofUWB （ultrawideband） radiation based on excitation of anterma arrays with bipolar voltage pulses. In the previously designed high-power UWB sourc...Investigations are directed to the development of high-power sources ofUWB （ultrawideband） radiation based on excitation of anterma arrays with bipolar voltage pulses. In the previously designed high-power UWB sources only one bipolar pulse former and different feeder systems for pulse distribution through the array elements were used. By means of this approach, a number of UWB sources were created with the bipolar voltage pulse length ranging from 0.2 to 2 ns and effective potential of radiation ranging from 0.4 to 3 MV. The approach has got a restriction related to the electrical breakdown in a bipolar voltage pulse former. A new approach to the creation of high-power UWB sources based on a multicharmel bipolar pulse former is suggested： the number of bipolar pulse formers is equal to the number of antennas in the array. The main problem in realization of this approach is a stable operation of bipolar pulse formers in order to ensure a coherent summation of radiated pulses in the far-field zone. The result of this work is the instability of-150 ps at the pulse length of 3 ns obtained in a one-channel bipolar pulse former indicating that the suggested approach is realizable.展开更多
Owing to its unique ability to capture volumetric tomographic information with a single light flash,optoacoustic(OA)tomography has recently demonstrated ultrafast imaging speeds ultimately limited by the ultrasound ti...Owing to its unique ability to capture volumetric tomographic information with a single light flash,optoacoustic(OA)tomography has recently demonstrated ultrafast imaging speeds ultimately limited by the ultrasound time-of-flight.The method's scalability and the achievable spatial resolution are yet limited by the narrow bandwidth of piezo-composite arrays currently employed for OA signal detection.Here we report on the first implementation of high-density spherical array technology based on flexible polyvinylidene difluoride films featuring ultrawideband(0.3-40 MHz)sub mm^(2)area elements,thus enabling real-time multi-scale volumetric imaging with 22-35μm spatial resolution,superior image fidelity and over an order of magnitude signal-to-noise enhancement compared to piezo-composite equivalents.We further demonstrate five-dimensional(spectroscopic,time-resolved,volumetric)imaging capabilities by visualizing fast stimulus-evoked cerebral oxygenation changes in mice and performing real-time functional angiography of deep human micro-vasculature.The new technology thus leverages the true potential of OA for quantitative high-resolution visualization of rapid bio-dynamics across scales.展开更多
An all-optical ultrawideband monocycle generator based on wavelength conversion in a semiconductor optical amplifier （SOA） and optical tunable delay in an optical delay line （ODL） is proposed and simulated. The sy...An all-optical ultrawideband monocycle generator based on wavelength conversion in a semiconductor optical amplifier （SOA） and optical tunable delay in an optical delay line （ODL） is proposed and simulated. The system achieves optically switchable in pulse polarity and tunable in both the pulsewidth and radio frequency （RF） spectrum.展开更多
文摘An ultrawideband reflectionless metamaterial absorber(MA)is proposed by replacing the metallic ground with the complementary split-ring resonator(CSRR)structure.The proposed MA exhibits-10 d B reflectivity spectrum from 1 GHz to 20 GHz,which maintains more than 90%absorption from 1.5 GHz to20 GHz.Furthermore,it achieves angle stability for TE and TM polarization at oblique incident angles up to 40°and 65°,respectively.To achieve broadband absorption spectrum,we have adopted a single-layer high-impedance surface(HIS)loaded with a double-layer magnetic material(MM)structure.To further realize the RCS reduction into a lower frequency range,we have employed the scattering cancellation technology into the traditional metallic ground.Finally,we have fabricated a sample exhibiting the 10 d B RCS reduction from 1 GHz to 20 GHz with a thickness of 10 mm.Measurement and simulation results confirm that the proposed MA exhibits excellent comprehensive performance,making it suitable for many practical applications.
基金support from the National Natural Science Foundation of China(Nos.51606158,11604311,and 12074151)Sichuan Science and Technology Program(No.2021JDRC0022)+3 种基金Natural Science Foundation of Fujian Province(No.2021J05202)Research Project of Fashu Foundation(No.MFK23006)Open Fund of the Key Laboratory of Metallurgical Equipment and Control Technology of Ministry of Education in Wuhan University of Science and Technology(No.MECOF2022B01)the project supported by Guangxi Key Laboratory of Precision Navigation Technology and Application,Guilin University of Electronic Technology(No.DH202321).
文摘The field of terahertz devices is important in terahertz technology.However,most of the current devices have limited functionality and poor performance.To improve device performance and achieve multifunctionality,we designed a terahertz device based on a combination of VO_(2)and metamaterials.This device can be tuned using the phase-transition characteristics of VO_(2),which is included in the triple-layer structure of the device,along with SiO_(2)and Au.The terahertz device exhibits various advantageous features,including broadband coverage,high absorption capability,dynamic tunability,simple structural design,polarization insensitivity,and incidentangle insensitivity.The simulation results showed that by controlling the temperature,the terahertz device achieved a thermal modulation range of spectral absorption from 0 to 0.99.At 313 K,the device exhibited complete reflection of terahertz waves.As the temperature increased,the absorption rate also increased.When the temperature reached 353 K,the device absorption rate exceeded 97.7%in the range of 5-8.55 THz.This study used the effective medium theory to elucidate the correlation between conductivity and temperature during the phase transition of VO_(2).Simultaneously,the variation in device performance was further elucidated by analyzing and depicting the intensity distribution of the electric field on the device surface at different temperatures.Furthermore,the impact of various structural parameters on device performance was examined,offering valuable insights and suggestions for selecting suitable parameter values in real-world applications.These characteristics render the device highly promising for applications in stealth technology,energy harvesting,modulation,and other related fields,thus showcasing its significant potential.
基金supported by the National Natural Science Foundation of China(Grant No.62005098)the Fundamental Research Funds for the Central University(Grant No.11623415)the Guangzhou Science and Technology Planning Project(Grant No.202201010320).
文摘In the field of short-range optical interconnects,the development of low-power-consumption,ultrawideband on-chip optical waveguide amplifiers is of critical importance.Central to this advancement is the creation of host materials that require low pump power and provide ultrabroadband emission capabilities.We introduce a tri-doped lanthanum aluminate glass(composition:5Er_(2)O_(3)-5Yb_(2)O_(3)-0.2Tm_(2)O_(3)-43.8La_(2)O_(3)-46Al_(2)O_(3)),which exhibits exceptional near-infrared(NIR)luminescence intensity,significantly outperforming other bands by 3 orders of magnitude.This glass can achieve an ultrawideband NIR gain spanning 478 nm,from 1510 to 1988 nm.Notably,the glass achieves positive optical gain with a low population inversion threshold(P>0.2),highlighting its efficiency and low-power consumption.The high glass transition temperature(Tg∼842°C)and large temperature difference(ΔT∼120°C)between Tg and the onset of crystallization(Tx)indicate excellent thermal stability,which is crucial for producing high-quality amorphous films for on-chip amplifiers.This research examines the unique energy levels and spectral properties of the Er^(3+)-Yb^(3+)-Tm^(3+) tri-doped glass,assessing its potential for use in ultrawideband on-chip optical waveguide amplifiers.This work lays the groundwork for low-power,ultrabroadband on-chip waveguide amplifiers,offering new avenues for short-range optical interconnect systems.
基金the Key Technology of Research on the Communication Network Based on TCP/IP(No.13ZA0156)
文摘A new design of ultrawideband(UWB) antenna of coplanar waveguide(CPW)-fed is proposed. The antenna is composed of a cross-shaped patch and house-shaped slot with the minimum dimension of 21 mm ×20 mm × 1.6 mm. The analysis of S11, VSWR, radiation pattern and surface current is discussed with HFSS simulation software, and also the effect of parameters is presented. Experimental results show that the bandwidth of the antenna covers 110.67%(3.3—11.6 GHz) of UWB range with return loss better than 10 dB. And the good impedance matching in frequency band confirms the antenna is a good candidate for the application of wireless system.
文摘Low frequency ultrawideband (LF UWB) synthetic aperture radar (SAR) has lately become of a particular interest to SAR community. Monostatic and bistatic LF UWB SAR system has the well foliage penetrating capability, high-resolution imaging and providing the increased information. In 2015, a monostatic and bistatic LF UWB SAR imaging experiment was conducted. In this experiment, the monostatic and bistatic data were collected simultaneously by operating a moving vehicle-based radar in the SAR mode, in conjunction with a stationary ground-based receiver. The aim was to investigate the imaging property of the bistatic LF UWB SAR system. The one pulse per second (1 PPS) signal in combination with the global position system (GPS) disciplined 100 MHz oscillator from the GPS receivers was used to implement the time and frequency synchronization in this SAR system. The bistatic SAR image was obtained by the subaperture spectrum-equilibrium method integrated with the fast factorized back projection (FFBP) algorithm. Bistatic experiment results are show to prove the validity of the bistatic LF UWB SAR imaging experiment.
文摘Investigations are directed to the development of high-power sources ofUWB （ultrawideband） radiation based on excitation of anterma arrays with bipolar voltage pulses. In the previously designed high-power UWB sources only one bipolar pulse former and different feeder systems for pulse distribution through the array elements were used. By means of this approach, a number of UWB sources were created with the bipolar voltage pulse length ranging from 0.2 to 2 ns and effective potential of radiation ranging from 0.4 to 3 MV. The approach has got a restriction related to the electrical breakdown in a bipolar voltage pulse former. A new approach to the creation of high-power UWB sources based on a multicharmel bipolar pulse former is suggested： the number of bipolar pulse formers is equal to the number of antennas in the array. The main problem in realization of this approach is a stable operation of bipolar pulse formers in order to ensure a coherent summation of radiated pulses in the far-field zone. The result of this work is the instability of-150 ps at the pulse length of 3 ns obtained in a one-channel bipolar pulse former indicating that the suggested approach is realizable.
基金supported by the Swiss National Science Foundation(310030_192757)the European Research Council(ERC-2015-CoG-682379)+2 种基金The development of the ultra-wideband ultrasonic antenna and the in vivo optoacoustic experiments were supported by the grants from the Russian Science Foundation(18-45-06006)the Helmholtz Association(HRSF-0020)The development of numerical algorithms for enhancement of angiographic optoacoustic images was partially supported by the grant from the Russian Science Foundation(19-75-10055)。
文摘Owing to its unique ability to capture volumetric tomographic information with a single light flash,optoacoustic(OA)tomography has recently demonstrated ultrafast imaging speeds ultimately limited by the ultrasound time-of-flight.The method's scalability and the achievable spatial resolution are yet limited by the narrow bandwidth of piezo-composite arrays currently employed for OA signal detection.Here we report on the first implementation of high-density spherical array technology based on flexible polyvinylidene difluoride films featuring ultrawideband(0.3-40 MHz)sub mm^(2)area elements,thus enabling real-time multi-scale volumetric imaging with 22-35μm spatial resolution,superior image fidelity and over an order of magnitude signal-to-noise enhancement compared to piezo-composite equivalents.We further demonstrate five-dimensional(spectroscopic,time-resolved,volumetric)imaging capabilities by visualizing fast stimulus-evoked cerebral oxygenation changes in mice and performing real-time functional angiography of deep human micro-vasculature.The new technology thus leverages the true potential of OA for quantitative high-resolution visualization of rapid bio-dynamics across scales.
文摘An all-optical ultrawideband monocycle generator based on wavelength conversion in a semiconductor optical amplifier （SOA） and optical tunable delay in an optical delay line （ODL） is proposed and simulated. The system achieves optically switchable in pulse polarity and tunable in both the pulsewidth and radio frequency （RF） spectrum.
