Broadband response metamaterial absorber(MMA)remains a challenge among researchers.A nanostructured new zero-indexed metamaterial(ZIM)absorber is presented in this study,constructed with a hexagonal shape resonator fo...Broadband response metamaterial absorber(MMA)remains a challenge among researchers.A nanostructured new zero-indexed metamaterial(ZIM)absorber is presented in this study,constructed with a hexagonal shape resonator for optical region applications.The design consists of a resonator and dielectric layers made with tungsten and quartz(Fused).The proposed absorbent exhibits average absorption of more than 0.8972(89.72%)within the visible wavelength of 450–600 nm and nearly perfect absorption of 0.99(99%)at 461.61 nm.Based on computational analysis,the proposed absorber can be characterized as ZIM.The developments of ZIM absorbers have demonstrated plasmonic resonance characteristics and a perfect impedance match.The incidence obliquity in typically the range of 0◦–90◦both in TE and TM mode with maximum absorbance is more than 0.8972(∼89.72%),and up to 45◦angular stability is suitable for solar cell applications,like exploiting solar energy.The proposed structure prototype is designed and simulated by studying microwave technology numerical computer simulation(CST)tools.The finite integration technique(FIT)based simulator CST and finite element method(FEM)based simulator HFSS also helps validate the numerical data of the proposed ZIM absorber.The proposed MMA design is appropriate for substantial absorption,wide-angle stability,absolute invisible layers,magnetic resonance imaging(MRI),color images,and thermal imaging applications.展开更多
A graphene-based tunable dual-band metamaterial absorber which is polarization insensitive is numerically pro- posed at mid-infrared frequencies. In numerical simulation the metamaterial absorber exhibits two absorpti...A graphene-based tunable dual-band metamaterial absorber which is polarization insensitive is numerically pro- posed at mid-infrared frequencies. In numerical simulation the metamaterial absorber exhibits two absorption peaks at the resonance wavelengths of 6.246 μm and 6.837μm when the Fermi level of graphene is fixed at 0. 6 eV. Absorption spectra at different Fermi levels of graphene are displayed and tuning functions are discussed in detail. Both the resonance wavelengths of the absorber blue shift with the increase in Fermi level of graphene. Moreover, the surface current distributions on the gold resonator and ground plane at the two resonance wavelengths are simulated to deeply understand the physical mechanism of resonance absorption.展开更多
A sensor based on an infrared dual-band polarization-insensitive metamaterial absorber is proposed,which consists of a square ring layer at the top,a silicon dielectric layer at the bottom,and a metal layer at the bot...A sensor based on an infrared dual-band polarization-insensitive metamaterial absorber is proposed,which consists of a square ring layer at the top,a silicon dielectric layer at the bottom,and a metal layer at the bottom.By using the finite element method(FEM),for the transverse electricity(TE)and transverse magnetic(TM)mode incidence,the absorption rates of the resonant point at 4.75μm are 0.950 and 0.943,and the absorption rates at 7.85μm can reach 0.997 and 0.998,respectively.Because of the symmetry of the structure,the absorber is not sensitive to polarization when it is vertically incident and can still maintain good absorption performance in a wide range of incidence angles.For commonly used aqueous solutions(sodium chloride,glucose,sucrose,etc.),the refractive index of the aqueous solution is in the range of 1.33 to 1.48 and the sensing test is performed.For the TE mode,the sensing sensitivity is about 2283.05 nm/RIU through linear fitting,and the quality factor Q is 108.38.For the TM mode,the sensing sensitivity is about 2371.43 nm/RIU through linear fitting,and the quality factor Q is 84.50,which has better sensing characteristics.The absorber sensor designed in this paper achieves high sensitivity in the infrared,has a high Q value,is easy to manufacture,and plays a huge advantage in the field of high-sensitivity detection.展开更多
This paper presents a tunable and polarization-insensitive wideband metamaterial absorber based on single-layer graphene.By comparing the simulated experimental data with theoretical derivations,it was found that the ...This paper presents a tunable and polarization-insensitive wideband metamaterial absorber based on single-layer graphene.By comparing the simulated experimental data with theoretical derivations,it was found that the absorbance of the material can be sustained above 90%in the frequency range of 2.78 to 7.14(4.36)THz,of which the absorption rate exceeds 99%in the frequency range of 4.1–4.54(0.44)THz,and remarkably,perfect absorption is achieved at4.32 THz.In the range of 2.78–7.14 THz,the average absorption rate is 96.1%,by adjusting the physical size of the graphene layer pattern,we can modify the working band gap of the absorber.By applying a voltage to modulate the Fermi level of graphene,we can increase the absorption bandwidth.When the chemical potential is 1.0 e V,at the bandwidth of 4.36 THz,its absorption rate exceeds 90%.The working principle of absorbing materials was deeply explored using the principles of electromagnetic field distribution and impedance adaptation.Through detailed analysis of different polarization states and incident angles,we found that the absorber is not sensitive to polarization due to its symmetrical structure,and found that it exhibits low sensitivity at incidence angles.In addition,after comparative analysis,significant differences were observed in the absorption efficiency of the absorber under various relaxation time conditions,and the obtained data were elaborated in detail using the carrier mechanism of plasma vibration.We found that in addition to obtaining an almost perfect absorber with wide band by adjusting the parameters,it is also feasible to obtain an approximately narrow band absorber by changing the relaxation time without having to remanufacture the structure.The absorber offers several advantages,including tunability,a wide absorption band,a high absorption rate,polarization insensitivity,and a simple structure.Therefore,this absorber exhibits great potential for absorption,monitoring,and sensing in the terahertz band.展开更多
Imaging spectrometers are most commonly used on satel- lites and aircrafts, including unmanned aerial vehicles （UAVs）, where the spare volume and weight are limited.
Polarization insensitive AlGaInAs InP semiconductor optical amplifier is realized at a wavelength of 1550nm.The active layer consists of three tensile strained wells with strain 0 40%.The amplifiers are fabricated ...Polarization insensitive AlGaInAs InP semiconductor optical amplifier is realized at a wavelength of 1550nm.The active layer consists of three tensile strained wells with strain 0 40%.The amplifiers are fabricated to ridge waveguide structure with 7° tilted cavity.The two facets are coated with two layers of anti reflection Ti 3O 5/Al 2O 3 films.Residual facet reflectivity is found to be less than 0 03%.The semiconductor optical amplifer exhibits 20dB of signal gain and 7 2dBm of saturation output power with an excellent polarization insensitivity (less than 0 8dB) at 200mA and 1540nm window.展开更多
Metasurfaces have emerged as a flexible platform for shaping the electromagnetic field via the tailoring phase,amplitude,and polarization at will.However,the chromatic aberration inherited from building blocks’diffra...Metasurfaces have emerged as a flexible platform for shaping the electromagnetic field via the tailoring phase,amplitude,and polarization at will.However,the chromatic aberration inherited from building blocks’diffractive nature plagues them when used in many practical applications.Current solutions for eliminating chromatic aberration usually rely on searching through many meta-atoms to seek designs that satisfy both phase and phase dispersion preconditions,inevitably leading to intensive design efforts.Moreover,most schemes are commonly valid for incidence with a specific spin state.Here,inspired by the Rayleigh criterion for spot resolution,we present a design principle for broadband achromatic and polarization-insensitive metalenses using two sets of anisotropic nanofins based on phase change material Ge2Sb2Se4Te1.By limiting the rotation angles of all nanofins to either 0 deg or 90 deg,the metalens with a suitable numerical aperture constructed by this fashion allows for achromatic and polarization-insensitive performance across the wavelength range of 4–5μm,while maintaining high focusing efficiency and diffraction-limited performance.We also demonstrate the versatility of our approach by successfully implementing the generation of broadband achromatic and polarization-insensitive focusing optical vortex.This work represents a major advance in achromatic metalenses and may find more applications in compact and chip-scale devices.展开更多
Polarization-insensitive optical modulators allow an external laser to be remotely interconnected by single-mode optical fibers while avoiding polarization controllers,which would be convenient and cost-effective for ...Polarization-insensitive optical modulators allow an external laser to be remotely interconnected by single-mode optical fibers while avoiding polarization controllers,which would be convenient and cost-effective for co-packaged optics,5G,and future 6G applications.In this article,a polarization-insensitive silicon intensity modulator is proposed and experimentally demonstrated based on two-dimensional centrally symmetric gratings,featuring a low polarization-dependent loss of 0.15 dB in minimum and polarization insensitivity of eye diagrams.The device exhibits a low fiber-to-fiber insertion loss of 9 dB and an electro-optic(EO)bandwidth of 49.8 GHz.A modulation speed of up to 224 Gb/s is also demonstrated.展开更多
A semiconductor optical amplifier gate based on tensile strained quasi bulk InGaAs is developed.At injection current of 80mA,a 3dB optical bandwidth of more than 85nm is achieved due to dominant band filling effect...A semiconductor optical amplifier gate based on tensile strained quasi bulk InGaAs is developed.At injection current of 80mA,a 3dB optical bandwidth of more than 85nm is achieved due to dominant band filling effect.Moreover,the most important is that very low polarization dependence of gain (<0 7dB),fiber to fiber lossless operation current (70～90mA) and a high extinction ratio (>50dB) are simultaneously obtained over this wide 3dB optical bandwidth (1520～1609nm) which nearly covers the spectral region of the whole C band (1525～1565nm) and the whole L band (1570～1610nm).The gating time is also improved by decreasing carrier lifetime.The wide band polarization insensitive SOA gate is promising for use in future dense wavelength division multiplexing (DWDM) communication systems.展开更多
The electromagnetically induced reflection(EIR)effect of graphene metamaterials has been investigated by finite difference time domain(FDTD)method.In this study,a metamaterial sandwich structure composed of silica(SiO...The electromagnetically induced reflection(EIR)effect of graphene metamaterials has been investigated by finite difference time domain(FDTD)method.In this study,a metamaterial sandwich structure composed of silica(SiO2),gold and graphene on terahertz band is designed.By changing the width of the two ribbons of graphene length and the incident angle of electromagnetic wave,the EIR effect of the structure is discussed,and it can be found that SiO2 is a kind of excellent dielectric material.The simulation results show that graphene metamaterial is not sensitive to polarized incident electromagnetic wave.Therefore,such EIR phenomena as insensitive polarization and large incident angle can be applied to optical communication filters and terahertz devices.展开更多
A modified double-split ring resonator and a modified triple-split ring resonator, which offer polarization-insensitive performance, are investigated, designed and fabricated. By displacing the two gaps of the convent...A modified double-split ring resonator and a modified triple-split ring resonator, which offer polarization-insensitive performance, are investigated, designed and fabricated. By displacing the two gaps of the conventional double- split ring resonator away from the center, the second resonant frequency for the 0° polarized wave and the resonant frequency for the 90° polarized wave become increasingly close to each other until they are finally identical. Theoretical and experimental results show that the modified double-split ring resonator and the modified triple-split ring resonator are insensitive to different polarized waves and show strong resonant frequency dips near 433 and 444OHz, respectively. The results of this work suggest new opportunities for the investigation and design of polarization-dependent terahertz devices based on split ring resonators.展开更多
It is desirable to have electromagnetic wave absorbers with ultrathin structural thickness and broader spectral absorption bandwidth with numerous applications in optoelectronics.In this paper,we theoretically propose...It is desirable to have electromagnetic wave absorbers with ultrathin structural thickness and broader spectral absorption bandwidth with numerous applications in optoelectronics.In this paper,we theoretically propose and numerically demonstrate a novel ultrathin nanostructure absorber composed of semiconductor nanoring array and a uniform gold substrate.The results show that the absorption covers the entire visible light region,achieving an average absorption rate more than 90%in a wavelength range from 300 nm to 740 nm and a nearly perfect absorption from 450 nm to 500 nm,and the polarization insensitivity performance is particularly great.The absorption performance is mainly caused by the electrical resonance and magnetic resonance of semiconductor nanoring array as well as the field coupling effects.Our designed broadband visible light absorber has wide application prospects in the fields of thermal photovoltaics and photodetectors.展开更多
We present a broadband and polarization-insensitive unidirectional imager that operates at the visible part of the spectrum,where image formation occurs in one direction,while in the opposite direction,it is blocked.T...We present a broadband and polarization-insensitive unidirectional imager that operates at the visible part of the spectrum,where image formation occurs in one direction,while in the opposite direction,it is blocked.This approach is enabled by deep learning-driven diffractive optical design with wafer-scale nano-fabrication using high-purity fused silica to ensure optical transparency and thermal stability.Our design achieves unidirectional imaging across three visible wavelengths(covering red,green,and blue parts of the spectrum),and we experimentally validated this broadband unidirectional imager by creating high-fidelity images in the forward direction and generating weak,distorted output patterns in the backward direction,in alignment with our numerical simulations.This work demonstrates wafer-scale production of diffractive optical processors,featuring 16 levels of nanoscale phase features distributed across two axially aligned diffractive layers for visible unidirectional imaging.This approach facilitates mass-scale production of~0.5 billion nanoscale phase features per wafer,supporting high-throughput manufacturing of hundreds to thousands of multi-layer diffractive processors suitable for large apertures and parallel processing of multiple tasks.Beyond broadband unidirectional imaging in the visible spectrum,this study establishes a pathway for artificial-intelligence-enabled diffractive optics with versatile applications,signaling a new era in optical device functionality with industrial-level,massively scalable fabrication.展开更多
Solar absorbers hold the capacity to transmute absorbed solar radiation spectrum into thermal energy,offering considerable promise for diverse applications,e.g.,electricity generation,heating,desalination,and energy s...Solar absorbers hold the capacity to transmute absorbed solar radiation spectrum into thermal energy,offering considerable promise for diverse applications,e.g.,electricity generation,heating,desalination,and energy storage,etc.The effective absorption of the solar radiation spectrum is critical for such applications.Hence,this paper introduces an absorber that is polarization-insensitive,broadband,and wide-angle.The absorber is designed by high-temperature-resistant materials for efficient solar energy collection,consisting of Cr and Fe square rings arrays,a SiO_(2)dielectric layer,and a Cr reflector.It exhibits excellent light-capturing capabilities,with an average absorption rate as high as 99.3%across the solar spectral range of 300–2400 nm.Moreover,the distributions of the magnetic and electric fields indicate that the distinctive nested square rings structure could effectively excite coupling resonance modes of surface plasmon resonances,cavity resonances,and magnetic resonances,which allow the proposed absorber to have broadband high absorption characteristics.Subsequently,the effects of different structures and geometrical parameters on the absorption performance are explored individually.Furthermore,the proposed solar absorber maintains high performance at large angles and is polarization-insensitive.We believe that this work not only deepens our understanding of coupling resonance modes but also suggests potential applications in the field of solar energy harvesting.展开更多
A polarization-insensitive, square split-ring resonator（SSRR） is simulated and experimented. By investigating the influence of the asymmetrical arm width in typical SSRRs, we find that the variation of the arm width...A polarization-insensitive, square split-ring resonator（SSRR） is simulated and experimented. By investigating the influence of the asymmetrical arm width in typical SSRRs, we find that the variation of the arm width enables a blue shift of the resonance frequency for the 0° polarized wave and a red shift of the resonance frequency for the 90° polarized wave. Thus, the resonance frequency for the 0° polarized wave and the resonance frequency for the 90° polarized wave will be identical by asymmetrically adjusting the arm width of the SSRR. Two modified, split-ring resonators（MSRRs） that are insensitive to the polarization with asymmetrical arm widths are designed, fabricated, and tested. Excellent agreement between the simulations and experiments for the MSRRs demonstrates the polarization insensitivity with asymmetrical arm widths. This work opens new opportunities for the investigation of polarization-insensitive, split-ring resonator metamaterials and will broaden the applications of split-ring resonators in various terahertz devices.展开更多
基金This work is supported by the Universiti Kebangsaan Malaysia research grant GUP-2020-074.
文摘Broadband response metamaterial absorber(MMA)remains a challenge among researchers.A nanostructured new zero-indexed metamaterial(ZIM)absorber is presented in this study,constructed with a hexagonal shape resonator for optical region applications.The design consists of a resonator and dielectric layers made with tungsten and quartz(Fused).The proposed absorbent exhibits average absorption of more than 0.8972(89.72%)within the visible wavelength of 450–600 nm and nearly perfect absorption of 0.99(99%)at 461.61 nm.Based on computational analysis,the proposed absorber can be characterized as ZIM.The developments of ZIM absorbers have demonstrated plasmonic resonance characteristics and a perfect impedance match.The incidence obliquity in typically the range of 0◦–90◦both in TE and TM mode with maximum absorbance is more than 0.8972(∼89.72%),and up to 45◦angular stability is suitable for solar cell applications,like exploiting solar energy.The proposed structure prototype is designed and simulated by studying microwave technology numerical computer simulation(CST)tools.The finite integration technique(FIT)based simulator CST and finite element method(FEM)based simulator HFSS also helps validate the numerical data of the proposed ZIM absorber.The proposed MMA design is appropriate for substantial absorption,wide-angle stability,absolute invisible layers,magnetic resonance imaging(MRI),color images,and thermal imaging applications.
基金Supported by the National Natural Science Foundation of China under Grant No 61001018the Natural Science Foundation of Shandong Province under Grant No ZR2012FM011+4 种基金the Shandong-Provincial Higher Educational Science and Technology Program under Grant No J11LG20the Qingdao City Innovative Leading Talent Plan under Grant No 13-CX-25the THz Science and Technology Foundation of China Academy of Engineering Physics under Grant No 201401the Qingdao Economic and Technical Development Zone Science and Technology Project under Grant No 2013-1-64the Shandong University of Science and Technology Foundation under Grant No YC140108
文摘A graphene-based tunable dual-band metamaterial absorber which is polarization insensitive is numerically pro- posed at mid-infrared frequencies. In numerical simulation the metamaterial absorber exhibits two absorption peaks at the resonance wavelengths of 6.246 μm and 6.837μm when the Fermi level of graphene is fixed at 0. 6 eV. Absorption spectra at different Fermi levels of graphene are displayed and tuning functions are discussed in detail. Both the resonance wavelengths of the absorber blue shift with the increase in Fermi level of graphene. Moreover, the surface current distributions on the gold resonator and ground plane at the two resonance wavelengths are simulated to deeply understand the physical mechanism of resonance absorption.
基金supported by the National Natural Science Foundation of China(Grant Nos.62075057 and 62075058).
文摘A sensor based on an infrared dual-band polarization-insensitive metamaterial absorber is proposed,which consists of a square ring layer at the top,a silicon dielectric layer at the bottom,and a metal layer at the bottom.By using the finite element method(FEM),for the transverse electricity(TE)and transverse magnetic(TM)mode incidence,the absorption rates of the resonant point at 4.75μm are 0.950 and 0.943,and the absorption rates at 7.85μm can reach 0.997 and 0.998,respectively.Because of the symmetry of the structure,the absorber is not sensitive to polarization when it is vertically incident and can still maintain good absorption performance in a wide range of incidence angles.For commonly used aqueous solutions(sodium chloride,glucose,sucrose,etc.),the refractive index of the aqueous solution is in the range of 1.33 to 1.48 and the sensing test is performed.For the TE mode,the sensing sensitivity is about 2283.05 nm/RIU through linear fitting,and the quality factor Q is 108.38.For the TM mode,the sensing sensitivity is about 2371.43 nm/RIU through linear fitting,and the quality factor Q is 84.50,which has better sensing characteristics.The absorber sensor designed in this paper achieves high sensitivity in the infrared,has a high Q value,is easy to manufacture,and plays a huge advantage in the field of high-sensitivity detection.
基金the support form the National Natural Science Foundation of China(Grant Nos.51606158,11604311,12074151)the Funded by the Guangxi Science and Technology Base and Talent Special Project(Grant No.AD21075009)+3 种基金the funded by the Sichuan Science and Technology Program(Grant No.2021JDRC0022)the Open Fund of the Key Laboratory for Metallurgical Equipment and Control Technology of Ministry of Education in Wuhan University of Science and Technology,China(Grant Nos.MECOF2022B01MECOF2023B04)the Project supported by Guangxi Key Laboratory of Precision Navigation Technology and Application,Guilin University of Electronic Technology(Grant No.DH202321)。
文摘This paper presents a tunable and polarization-insensitive wideband metamaterial absorber based on single-layer graphene.By comparing the simulated experimental data with theoretical derivations,it was found that the absorbance of the material can be sustained above 90%in the frequency range of 2.78 to 7.14(4.36)THz,of which the absorption rate exceeds 99%in the frequency range of 4.1–4.54(0.44)THz,and remarkably,perfect absorption is achieved at4.32 THz.In the range of 2.78–7.14 THz,the average absorption rate is 96.1%,by adjusting the physical size of the graphene layer pattern,we can modify the working band gap of the absorber.By applying a voltage to modulate the Fermi level of graphene,we can increase the absorption bandwidth.When the chemical potential is 1.0 e V,at the bandwidth of 4.36 THz,its absorption rate exceeds 90%.The working principle of absorbing materials was deeply explored using the principles of electromagnetic field distribution and impedance adaptation.Through detailed analysis of different polarization states and incident angles,we found that the absorber is not sensitive to polarization due to its symmetrical structure,and found that it exhibits low sensitivity at incidence angles.In addition,after comparative analysis,significant differences were observed in the absorption efficiency of the absorber under various relaxation time conditions,and the obtained data were elaborated in detail using the carrier mechanism of plasma vibration.We found that in addition to obtaining an almost perfect absorber with wide band by adjusting the parameters,it is also feasible to obtain an approximately narrow band absorber by changing the relaxation time without having to remanufacture the structure.The absorber offers several advantages,including tunability,a wide absorption band,a high absorption rate,polarization insensitivity,and a simple structure.Therefore,this absorber exhibits great potential for absorption,monitoring,and sensing in the terahertz band.
基金supported by the Industrial Projects of Public Welfare Technology Research(No.2014C31088)the National Natural Science Foundation of China(No.61535010)
文摘Imaging spectrometers are most commonly used on satel- lites and aircrafts, including unmanned aerial vehicles （UAVs）, where the spare volume and weight are limited.
文摘Polarization insensitive AlGaInAs InP semiconductor optical amplifier is realized at a wavelength of 1550nm.The active layer consists of three tensile strained wells with strain 0 40%.The amplifiers are fabricated to ridge waveguide structure with 7° tilted cavity.The two facets are coated with two layers of anti reflection Ti 3O 5/Al 2O 3 films.Residual facet reflectivity is found to be less than 0 03%.The semiconductor optical amplifer exhibits 20dB of signal gain and 7 2dBm of saturation output power with an excellent polarization insensitivity (less than 0 8dB) at 200mA and 1540nm window.
基金supported by the National Natural Science Foundation of China(Grant No.12004347)the Scientific and Technological Project in Henan Province(Grant Nos.222102210063 and 232102320057)+2 种基金the Aeronautical Science Foundation of China(Grant Nos.2020Z073055002 and 2019ZF055002)the Innovation and Entrepreneurship Training Program for College Students(Grant Nos.202210485007 and 202210485044)the Graduate Education Innovation Program Foundation(Grant No.2022CX53).
文摘Metasurfaces have emerged as a flexible platform for shaping the electromagnetic field via the tailoring phase,amplitude,and polarization at will.However,the chromatic aberration inherited from building blocks’diffractive nature plagues them when used in many practical applications.Current solutions for eliminating chromatic aberration usually rely on searching through many meta-atoms to seek designs that satisfy both phase and phase dispersion preconditions,inevitably leading to intensive design efforts.Moreover,most schemes are commonly valid for incidence with a specific spin state.Here,inspired by the Rayleigh criterion for spot resolution,we present a design principle for broadband achromatic and polarization-insensitive metalenses using two sets of anisotropic nanofins based on phase change material Ge2Sb2Se4Te1.By limiting the rotation angles of all nanofins to either 0 deg or 90 deg,the metalens with a suitable numerical aperture constructed by this fashion allows for achromatic and polarization-insensitive performance across the wavelength range of 4–5μm,while maintaining high focusing efficiency and diffraction-limited performance.We also demonstrate the versatility of our approach by successfully implementing the generation of broadband achromatic and polarization-insensitive focusing optical vortex.This work represents a major advance in achromatic metalenses and may find more applications in compact and chip-scale devices.
基金National Natural Science Foundation of China(62341508,61974099,62022081)Youth Innovation Promotion Association of the Chinese Academy of Sciences(Y2022045)+1 种基金Major Key Project of Peng Cheng LaboratoryOpen Project of Tianjin Key Laboratory of Optoelectronic Detection Technology and System(2024LODTS104)。
文摘Polarization-insensitive optical modulators allow an external laser to be remotely interconnected by single-mode optical fibers while avoiding polarization controllers,which would be convenient and cost-effective for co-packaged optics,5G,and future 6G applications.In this article,a polarization-insensitive silicon intensity modulator is proposed and experimentally demonstrated based on two-dimensional centrally symmetric gratings,featuring a low polarization-dependent loss of 0.15 dB in minimum and polarization insensitivity of eye diagrams.The device exhibits a low fiber-to-fiber insertion loss of 9 dB and an electro-optic(EO)bandwidth of 49.8 GHz.A modulation speed of up to 224 Gb/s is also demonstrated.
文摘A semiconductor optical amplifier gate based on tensile strained quasi bulk InGaAs is developed.At injection current of 80mA,a 3dB optical bandwidth of more than 85nm is achieved due to dominant band filling effect.Moreover,the most important is that very low polarization dependence of gain (<0 7dB),fiber to fiber lossless operation current (70～90mA) and a high extinction ratio (>50dB) are simultaneously obtained over this wide 3dB optical bandwidth (1520～1609nm) which nearly covers the spectral region of the whole C band (1525～1565nm) and the whole L band (1570～1610nm).The gating time is also improved by decreasing carrier lifetime.The wide band polarization insensitive SOA gate is promising for use in future dense wavelength division multiplexing (DWDM) communication systems.
基金Research Project of Anhui Province Education Department(No.KJ2020A0684)Innovation and Entrepreneurship Training Program for College Students(Nos.S201910375072,201910375050,201910375052,202010375030)。
文摘The electromagnetically induced reflection(EIR)effect of graphene metamaterials has been investigated by finite difference time domain(FDTD)method.In this study,a metamaterial sandwich structure composed of silica(SiO2),gold and graphene on terahertz band is designed.By changing the width of the two ribbons of graphene length and the incident angle of electromagnetic wave,the EIR effect of the structure is discussed,and it can be found that SiO2 is a kind of excellent dielectric material.The simulation results show that graphene metamaterial is not sensitive to polarized incident electromagnetic wave.Therefore,such EIR phenomena as insensitive polarization and large incident angle can be applied to optical communication filters and terahertz devices.
基金Supported by the National High-Technology Research and Development Program of China under Grant No 2011AA010204the National Natural Science Foundation of China under Grant No 91438118
文摘A modified double-split ring resonator and a modified triple-split ring resonator, which offer polarization-insensitive performance, are investigated, designed and fabricated. By displacing the two gaps of the conventional double- split ring resonator away from the center, the second resonant frequency for the 0° polarized wave and the resonant frequency for the 90° polarized wave become increasingly close to each other until they are finally identical. Theoretical and experimental results show that the modified double-split ring resonator and the modified triple-split ring resonator are insensitive to different polarized waves and show strong resonant frequency dips near 433 and 444OHz, respectively. The results of this work suggest new opportunities for the investigation and design of polarization-dependent terahertz devices based on split ring resonators.
基金Project supported by the Natural Science Foundation of Guangdong Province,China(Grant Nos.2018A030313854 and 2016A030313851)
文摘It is desirable to have electromagnetic wave absorbers with ultrathin structural thickness and broader spectral absorption bandwidth with numerous applications in optoelectronics.In this paper,we theoretically propose and numerically demonstrate a novel ultrathin nanostructure absorber composed of semiconductor nanoring array and a uniform gold substrate.The results show that the absorption covers the entire visible light region,achieving an average absorption rate more than 90%in a wavelength range from 300 nm to 740 nm and a nearly perfect absorption from 450 nm to 500 nm,and the polarization insensitivity performance is particularly great.The absorption performance is mainly caused by the electrical resonance and magnetic resonance of semiconductor nanoring array as well as the field coupling effects.Our designed broadband visible light absorber has wide application prospects in the fields of thermal photovoltaics and photodetectors.
基金Ozcan Lab at UCLA acknowledges the U.S.Department of Energy(DOE),Office of Basic Energy Sciences,Division of Materials Sciences and Engineering under award no.DE-SC0023088.
文摘We present a broadband and polarization-insensitive unidirectional imager that operates at the visible part of the spectrum,where image formation occurs in one direction,while in the opposite direction,it is blocked.This approach is enabled by deep learning-driven diffractive optical design with wafer-scale nano-fabrication using high-purity fused silica to ensure optical transparency and thermal stability.Our design achieves unidirectional imaging across three visible wavelengths(covering red,green,and blue parts of the spectrum),and we experimentally validated this broadband unidirectional imager by creating high-fidelity images in the forward direction and generating weak,distorted output patterns in the backward direction,in alignment with our numerical simulations.This work demonstrates wafer-scale production of diffractive optical processors,featuring 16 levels of nanoscale phase features distributed across two axially aligned diffractive layers for visible unidirectional imaging.This approach facilitates mass-scale production of~0.5 billion nanoscale phase features per wafer,supporting high-throughput manufacturing of hundreds to thousands of multi-layer diffractive processors suitable for large apertures and parallel processing of multiple tasks.Beyond broadband unidirectional imaging in the visible spectrum,this study establishes a pathway for artificial-intelligence-enabled diffractive optics with versatile applications,signaling a new era in optical device functionality with industrial-level,massively scalable fabrication.
基金supported by the National Natural Science Foundation of China(No.62075058)Natural Science Foundation of Henan Province(No.222300420011)the Program for Innovative Research Team(in Science and Technology)in University of Henan Province(No.23IRTSTHN013).
文摘Solar absorbers hold the capacity to transmute absorbed solar radiation spectrum into thermal energy,offering considerable promise for diverse applications,e.g.,electricity generation,heating,desalination,and energy storage,etc.The effective absorption of the solar radiation spectrum is critical for such applications.Hence,this paper introduces an absorber that is polarization-insensitive,broadband,and wide-angle.The absorber is designed by high-temperature-resistant materials for efficient solar energy collection,consisting of Cr and Fe square rings arrays,a SiO_(2)dielectric layer,and a Cr reflector.It exhibits excellent light-capturing capabilities,with an average absorption rate as high as 99.3%across the solar spectral range of 300–2400 nm.Moreover,the distributions of the magnetic and electric fields indicate that the distinctive nested square rings structure could effectively excite coupling resonance modes of surface plasmon resonances,cavity resonances,and magnetic resonances,which allow the proposed absorber to have broadband high absorption characteristics.Subsequently,the effects of different structures and geometrical parameters on the absorption performance are explored individually.Furthermore,the proposed solar absorber maintains high performance at large angles and is polarization-insensitive.We believe that this work not only deepens our understanding of coupling resonance modes but also suggests potential applications in the field of solar energy harvesting.
基金supported by the National High Technology Research and Development Program of China (No. 2011AA010204)the National Natural Science Foundation of China (Nos. 91438118 and 61370011)the Fundamental Research Funds for the Central Universities of China (No. ZYGX2014J037)
文摘A polarization-insensitive, square split-ring resonator（SSRR） is simulated and experimented. By investigating the influence of the asymmetrical arm width in typical SSRRs, we find that the variation of the arm width enables a blue shift of the resonance frequency for the 0° polarized wave and a red shift of the resonance frequency for the 90° polarized wave. Thus, the resonance frequency for the 0° polarized wave and the resonance frequency for the 90° polarized wave will be identical by asymmetrically adjusting the arm width of the SSRR. Two modified, split-ring resonators（MSRRs） that are insensitive to the polarization with asymmetrical arm widths are designed, fabricated, and tested. Excellent agreement between the simulations and experiments for the MSRRs demonstrates the polarization insensitivity with asymmetrical arm widths. This work opens new opportunities for the investigation of polarization-insensitive, split-ring resonator metamaterials and will broaden the applications of split-ring resonators in various terahertz devices.
