A rigid aromatic diamine monomer containing di-tert-butylbenzene and dimethyl groups,3,3'-dimethyl-4,4'-diaminophenyl-3",5"-di-tert-butyltoluene,was successfully synthesized by a simple coupling reac...A rigid aromatic diamine monomer containing di-tert-butylbenzene and dimethyl groups,3,3'-dimethyl-4,4'-diaminophenyl-3",5"-di-tert-butyltoluene,was successfully synthesized by a simple coupling reaction using 3,5-di-tert-butylbenzaldehyde and o-toluidine as starting materials.A series of novel polyimides(PI 3a-3c)with large pendant groups were prepared with the obtained diamine monomer and three different commercial aromatic dianhydrides(3,3',4,4'-biphenyltetracarboxylic dianhydride,4,4'-oxydiphthalic anhydride,and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride)by one-step high temperature polycondensation.The prepared polyimides exhibited high solubility and good membrane forming ability:they could be dissolved not only in some high boiling solvents such as DMF,NMP,DMAc,and m-Cresol at room temperature,but also in some low boiling solvents such as CHCl3,CH2Cl2,and THF.Their solubility in most solvents could exceed 10 wt%,and the flexible membranes could be obtained by casting their solutions.The prepared membranes exhibited good gas separation properties.The permeability coefficients of PI 3c for CO2 and O2 were up to 124.6 and 42.8 barrer,respectively,and the selectivity coefficients for CO2/CH4 and O2/N2 were 14.7 and 3.3,respectively.The membranes had light color and good optical transmission.Their optical transmittance at 450 nm wavelength was in the range of 67%-79%,and the cutoff wavelength was in the range of 310-348 nm.They also had good thermal properties with glass transition temperature(Tg)values in the range of 264-302℃.In addition,these membranes possessed good mechanical properties with tensile strength ranging between 77.8-87.4 MPa,initial modulus ranging between 1.69-1.82 GPa,and elongation at break ranging between 4.8%-6.1%.展开更多
We study the ultraslow optical solitons in a resonant three-level atomic system via electromagnetically induced transparency under a density-matrix （DM） approach. The results of linear and nonlinear optical properti...We study the ultraslow optical solitons in a resonant three-level atomic system via electromagnetically induced transparency under a density-matrix （DM） approach. The results of linear and nonlinear optical properties are compared with those obtained by using an amplitude variable （AV） approach. It is found that the results for both approaches are the same in the linear regime if the corresponding relations between the population-coherence decay rates in the DM approach and the energy-level decay rates in the AV approach are appropriately imposed. However, in the nonlinear regime there is a small difference for the self-phase modulation coefficient of the nonlinear SchrSdinger equation that governs the time evolution of probe pulse envelope. All analytical predicts are checked by numerical simulations.展开更多
Optical nanofiber(ONF)is a special tool to achieve the interaction between light and matter with ultralow power.In this paper,we demonstrate V-type electromagnetically induced transparency(EIT)in cold atoms trapped by...Optical nanofiber(ONF)is a special tool to achieve the interaction between light and matter with ultralow power.In this paper,we demonstrate V-type electromagnetically induced transparency(EIT)in cold atoms trapped by an ONFbased two-color optical lattice.At an optical depth of 7.35,90%transmission can be achieved by only 7.7 pW coupling power.The EIT peak and linewidth are investigated as a function of the coupling optical power.By modulating the pWlevel control beam of the ONF-EIT system in sequence,we further achieve efficient and high contrast control of the probe transmission,as well as its potential application in the field of quantum communication and quantum information science by using one-dimensional atomic chains.展开更多
A kind of photonic crystal structure with modulation of the refractive index is investigated both experimentally and theoretically for exploiting electromagnetically induced transparency（EIT）.The combination of EIT ...A kind of photonic crystal structure with modulation of the refractive index is investigated both experimentally and theoretically for exploiting electromagnetically induced transparency（EIT）.The combination of EIT with periodically modulated refractive index medium gives rise to high efficiency reflection as well as forbidden transmission in a threelevel atomic system coupled by standing wave.We show an accurate theoretical simulation via transfer-matrix theory,automatically accounting for multilayer reflections,thus fully demonstrate the existence of photonic crystal structure in atomic vapor.展开更多
A graphene-based metamaterial for THz plasmon induced transparency(PIT) is presented and numerically studied in this paper, which consists of two horizontal graphene strips attached to a continuous vertical wire separ...A graphene-based metamaterial for THz plasmon induced transparency(PIT) is presented and numerically studied in this paper, which consists of two horizontal graphene strips attached to a continuous vertical wire separately. The calculated surface current distributions demonstrate that the distinct PIT window results from the near-field coupling of two bright modes. To explore the physical mechanism of PIT effect, we employ the coupled Lorentz oscillator model. The transmission spectra obtained with this model fits well with the simulation results. The performance of the PIT system can be controlled through the geometry parameters of graphene strips. Moreover, the transparency window can be dynamically tuned by varying the Fermi energy and the carrier mobility of the graphene strips. The slow light effect is also explored in our proposed structure and it can achieve 1.25 ps when Fermi energy is 1.3 eV. Finally, the position of the transmission window with the variation of the nearby medium refractive index is examined. Such a proposed graphene-based PIT system may have great potential applications in photonic devices.展开更多
In the face of deteriorating environmental conditions in the world,water quality control is an urgent task.It can be solved by creating sensors with high accuracy and low cost,which requires the development of fundame...In the face of deteriorating environmental conditions in the world,water quality control is an urgent task.It can be solved by creating sensors with high accuracy and low cost,which requires the development of fundamentally new radiophysical methods that take advantage of the optical,microwave and millimeter wavelengths that have a significantly greater sensitivity to low concentrations of pollutants and a lower inertia.The article presents prototypes of measuring cells of the microwave and optical ranges as well as the results of an experimental study of water of various degrees of pollution with their help.The results show that the use of the highly sensitive method of capillary-waveguide resonance makes it possible to detect the presence of micro impurities in water with concentrations up to0.1%and to identify water even from sources of various natural origins.In addition,the use of measurements at several frequencies in the optical range will make it possible to solve the problem of creating water control sensors with high sensitivity to pollution and low cost.It can be concluded that the possibility of complex use of multiwave sensors(optical,infrared and microwave ranges)allows to increase the sensitivity and reliability of water quality assessment.展开更多
An approach for solving the excitonic absorption in a semiconductor quantum well driven by an intense terahertz field is presented.The formalism relies on the stationary single-photon Schro¨dinger equation in the...An approach for solving the excitonic absorption in a semiconductor quantum well driven by an intense terahertz field is presented.The formalism relies on the stationary single-photon Schro¨dinger equation in the full quantum mechanical framework.The optical absorption dynamics in both weak and strong couplings are discussed and compared.The excitonic absorption spectra show the Autler-Townes doublets for the resonance terahertz field,a replica peak for the non-resonance terahertz field,and the electromagnetically induced transparency phenomenon for modulating the decay rate of the second electron state in the weak coupling.In particular,the electromagnetically induced transparency phenomenon window range is discussed.In the strong coupling region,the multi-order energy level resonance splitting due to the strong optical field is found.There are three（non-resonance terahertz field） or four（resonance terahertz field） peaks in the optical absorption spectra.This work provides a simple and convenient approach to deal with the optical absorption in the exciton system.展开更多
Optical nanofiber(ONF) is a special tool for effectively controlling coupling of light and atoms. In this paper, we study the ladder-type electromagnetically induced transparent(EIT) under ultralow power level in a wa...Optical nanofiber(ONF) is a special tool for effectively controlling coupling of light and atoms. In this paper, we study the ladder-type electromagnetically induced transparent(EIT) under ultralow power level in a warm cesium vapor by observing the transmission of ONF that couples the 6 S → 6 P Cs atoms in the presence of a 6 P → 8 S control beam through the same fiber. The linewidth and transmission of the EIT signal are investigated at different intensities of the control laser. In addition, we theoretically study the nonlinear interaction at the ONF interface using the multi-level density matrix equations, and obtain good agreements between theory and experiments. The results may have great significance for further study of optical nonlinear effect at low power level.展开更多
In a Doppler-broadened ladder-type cesium atomic system （6S1/2 6P3/2-8S1/2）, this paper characterizes electro- magnetically induced transparency （EIT） in two different experimental arrangements, and investigates t...In a Doppler-broadened ladder-type cesium atomic system （6S1/2 6P3/2-8S1/2）, this paper characterizes electro- magnetically induced transparency （EIT） in two different experimental arrangements, and investigates the influence of the double-resonance optical-pumping （DROP） effect on EIT in both arrangements. When the probe laser is weak, DROP is explicitly suppressed. When the probe laser is moderate, population of the intermediate level （6P3/2 FI = 5） is remarkable, therefore DROP is mixed with EIT. An interesting bimodal spectrum with the broad component due to DROP and the narrow part due to EIT has been clearly observed in cesium 6S1/2 F = 4-6P3/2 F^1= 5-8S1/2 F^11 = 4 transitions.展开更多
We study the features of electromagnetically induced transparency（EIT） in a single Λ-type three-level atom placed in a high-finesse cavity under the action of a coupling laser and a probe laser.Our calculations sho...We study the features of electromagnetically induced transparency（EIT） in a single Λ-type three-level atom placed in a high-finesse cavity under the action of a coupling laser and a probe laser.Our calculations show that three transparency windows appear when the pump strength is large enough.This can be explained by the residual pump in the cavity mostly resulting in energy splitting.The level ｜3 is split into four slightly different energy levels,and interference takes place between the excitation pathways.Furthermore,it is also shown that the frequencies of the EIT windows can be tuned by changing the coupling field detuning 2,and that the reflection profile is very sensitive to the cavity field detuning △c.展开更多
In this paper, we propose and analyze an optical multi-wave mixing scheme for the generation of coherent light in a five-level atomic system in the context of electromagnetically induced transparency. A detailed semic...In this paper, we propose and analyze an optical multi-wave mixing scheme for the generation of coherent light in a five-level atomic system in the context of electromagnetically induced transparency. A detailed semiclassical study of the propagation of generated mixing and probe fields is demonstrated. The analytical dependence of the generated mixing field on the probe field and the respective detuning is predicted. Such a nonlinear optical process can be used for generating short-wavelength radiation at low pump intensities.展开更多
We theoretically investigate an enhanced electromagnetically induced transparency （EIT） cooling method by introduc- ing a high finesse cavity. We find that the quantum destructive interference that is induced by the...We theoretically investigate an enhanced electromagnetically induced transparency （EIT） cooling method by introduc- ing a high finesse cavity. We find that the quantum destructive interference that is induced by the EIT effect and the cavity coupling can eliminate all of the heating effects in the cooling process by choosing appropriate parameters. Compared with the EIT cooling scheme, a lower final temperature can be obtained under the same conditions in our scheme.展开更多
According to density matrix equations of the interaction between light and matter, the expression for the suscep- tibility of the Eu^3＋ ：Y2SiO5 crystal is obtained. When the control field is a Gaussian beam, we inve...According to density matrix equations of the interaction between light and matter, the expression for the suscep- tibility of the Eu^3＋ ：Y2SiO5 crystal is obtained. When the control field is a Gaussian beam, we investigate and analyze the influence of probe detuning, the Rabi frequency of the control field and the laser line width on the transverse optical properties. We also analyze the influence of the dope-ion concentration on electromagnetieally induced transparency （EIT）. The analysis result indicates that the transmission is not a monotonic function of the dope-ion concentration. Based on the influences of various parameters on the transverse optical properties, we choose the appropriate parameters to realize the desired EIT and gradient refractive index, which has applications in focusing and imaging.展开更多
Optical microscopy,optical transmission spectra,sweep electron microscope,electron microprobe analysis etc.were used to study the appearance and machanism of formation of the defects caused by impurities which serious...Optical microscopy,optical transmission spectra,sweep electron microscope,electron microprobe analysis etc.were used to study the appearance and machanism of formation of the defects caused by impurities which seriously affect the optical transparency of doped bismuth germanate.The methods of improving the optical transparency were also discussed.展开更多
We show that an optical transparency can be obtained by using only one single magneto-optical ring resonator. This effect is based on the splitting of counterclockwise and clockwise modes in the ring resonator. Within...We show that an optical transparency can be obtained by using only one single magneto-optical ring resonator. This effect is based on the splitting of counterclockwise and clockwise modes in the ring resonator. Within a proposed resonator-waveguide configuration the superposition between the two degeneracy broken modes produces a transparency window,which can be closed, open, and modified by tuning the applied magnetic field. This phenomenon is an analogue of Autler–Townes splitting, and the magnetic field is equivalent to the strong external pump field. We provide a theoretic analysis on the induced transparency, and numerically demonstrate the effect using full-wave simulation. Feasible implication of this effect and its potential applications are also discussed.展开更多
BACKGROUND Atypical optic neuritis,consisting of neuromyelitis optica spectrum disorders(NMOSD)or myelin oligodendrocyte glycoprotein antibody disease(MOGAD),has a very similar presentation but different prognostic im...BACKGROUND Atypical optic neuritis,consisting of neuromyelitis optica spectrum disorders(NMOSD)or myelin oligodendrocyte glycoprotein antibody disease(MOGAD),has a very similar presentation but different prognostic implications and longterm management strategies.Vascular and metabolic factors are being thought to play a role in such autoimmune neuro-inflammatory disorders,apart from the obvious immune mediated damage.With the advent of optical coherence tomography angiography(OCTA),it is easy to pick up on these subclinical macular microvascular and structural changes.AIM To study the macular microvascular and structural changes on OCTA in atypical optic neuritis.METHODS This observational cross-sectional study involved 8 NMOSD and 17 MOGAD patients,diagnosed serologically,as well as 10 healthy controls.Macular vascular density(MVD)and ganglion cell+inner plexiform layer thickness(GCIPL)were studied using OCTA.RESULTS There was a significant reduction in MVD in NMOSD and MOGAD affected as well as unaffected eyes when compared with healthy controls.NMOSD and MOGAD affected eyes had significant GCIPL thinning compared with healthy controls.NMOSD unaffected eyes did not show significant GCIPL thinning compared to healthy controls in contrast to MOGAD unaffected eyes.On comparing NMOSD with MOGAD,there was no significant difference in terms of MVD or GCIPL in the affected or unaffected eyes.CONCLUSION Although significant microvascular and structural changes are present on OCTA between atypical optic neuritis and normal patients,they could not help in differentiating between NMOSD and MOGAD cases.展开更多
Over the past several decades,much research effort has been dedicated to the study of optical windows,with two primary themes emerging as key focuses.The first of these centers on investigating the optical properties ...Over the past several decades,much research effort has been dedicated to the study of optical windows,with two primary themes emerging as key focuses.The first of these centers on investigating the optical properties of typical transparent single crystals under shock or ramp compression,which helps in the selection of appropriate optical windows for high-pressure experiments.The second involves the exploration of novel optical windows,particularly transparent polycrystalline ceramics,which not only match the shock impedance of the samples,but also preserve transparency under dynamic compression.In this study,we first integrate existing research on the evolution of optical properties in transparent single crystals and polycrystalline ceramics subjected to shock or ramp loading,proposing a mechanism that links mesoscopic damage to macroscopic optical transparency.Subsequently,through a systematic integration of experiments and computational analyses on polycrystalline transparent ceramics,we demonstrate that shock transparency can be enhanced by optimizing grain size and that shock impedance can be designed via compositional tuning.Notably,our results reveal that nano-grained MgAl_(2)O_(4) ceramics exhibit outstanding optical transparency under high shock pressures,highlighting a promising strategy for designing optical windows that retain transparency under extreme dynamic loading conditions.展开更多
Liquid crystal Pacharatnam-Berry phase optical elements(PBOEs)have found promising applications in augmented reality and virtual reality because of their slim formfactor,lightweight,and high optical efficiency.However...Liquid crystal Pacharatnam-Berry phase optical elements(PBOEs)have found promising applications in augmented reality and virtual reality because of their slim formfactor,lightweight,and high optical efficiency.However,chromatic aberration remains a serious longstanding problem for diffractive optics,hindering their broader adoption.To overcome the chromatic aberrations for red,green and blue(RGB)light sources,in this paper,we propose a counterintuitive multi-twist structure to achieve narrowband PBOEs without crosstalk,which plays a vital role to eliminate the chromatic aberration.The performance of our designed and fabricated narrowband Pacharatnam-Berry lenses(PBLs)aligns well with our simulation results.Furthermore,in a feasibility demonstration experiment using a laser projector,our proposed PBL system indeed exhibits a diminished chromatic aberration as compared to a broadband PBL.Additionally,polarization raytracing is implemented to demonstrate the versatility of the multi-twist structure for designing any RGB wavelengths with high contrast ratios.This analysis explores the feasibility of using RGB laser lines and quantum dot light-emitting diodes.Overall,our approach enables high optical efficiency,low fabrication complexity,and high degree of design freedom to accommodate any liquid crystal material and RGB light sources,holding immense potential for widespread applications of achromatic PBOEs.展开更多
Optical network-on-chip(ONoC) systems have emerged as a promising solution to overcome limitations of traditional electronic interconnects. Efficient ONoC architectures rely on optical routers, enabling high-speed dat...Optical network-on-chip(ONoC) systems have emerged as a promising solution to overcome limitations of traditional electronic interconnects. Efficient ONoC architectures rely on optical routers, enabling high-speed data transfer, efficient routing, and scalability. This paper presents a comprehensive survey analyzing optical router designs, specifically microring resonators(MRRs), Mach-Zehnder interferometers(MZIs), and hybrid architectures. Selected comparison criteria, chosen for their critical importance, significantly impact router functionality and performance. By emphasizing these criteria, valuable insights into the strengths and limitations of different designs are gained, facilitating informed decisions and advancements in optical networking. While other factors contribute to performance and efficiency, the chosen criteria consistently address fundamental elements, enabling meaningful evaluation. This work serves as a valuable resource for beginners, providing a solid foundation in understanding ONoC and optical routers. It also offers an in-depth survey for experts, laying the groundwork for further exploration. Additionally, the importance of considering design constraints and requirements when selecting an optimal router design is highlighted. Continued research and innovation will enable the development of efficient optical router solutions that meet the evolving needs of modern computing systems. This survey underscores the significance of ongoing advancements in the field and their potential impact on future technologies.展开更多
In this study,we developed a single-beam optical trap-based surface-enhanced Raman scattering(SERS)optofluidic molecular fingerprint spectroscopy detection system.This system utilizes a single-beam optical trap to con...In this study,we developed a single-beam optical trap-based surface-enhanced Raman scattering(SERS)optofluidic molecular fingerprint spectroscopy detection system.This system utilizes a single-beam optical trap to concentrate free silver nanoparticles(AgNPs)within an optofluidic chip,significantly enhancing SERS performance.We investigated the optical field distribution characteristics within the tapered fiber using COMSOL simulation software and established a MATLAB simulation model to validate the single-beam optical trap's effectiveness in capturing AgNPs,demonstrating the theoretical feasibility of our approach.To verify the particle capture efficacy of the system,we experimentally controlled the optical trap's on-off state to manage the capture and release of particles precisely.The experimental results indicated that the Raman signal intensity in the capture state was significantly higher than in the non-capture state,confirming that the single-beam optical trap effectively enhances the SERS detection capability of the optofluidic detection system.Furthermore,we employed Raman mapping techniques to investigate the impact of the capture area on the SERS effect,revealing that the spectral intensity of molecular fingerprints in the laser-trapping region is significantly improved.We successfully detected the Raman spectrum of crystal violet at a concentration of 10^(−9)mol/L and pesticide thiram at a concentration of 10^(−5)mol/L,further demonstrating the ability of the single-beam optical trap in enhancing the molecular fingerprint spectrum identification capability of the SERS optofluidic chips.The optical trapping SERS optofluidic detection system developed in this study,as a key component of an integrated optoelectronic sensing system,holds the potential for integration with portable high-power lasers and high-performance Raman spectrometers.This integration is expected to advance highly integrated technologies and significantly enhance the overall performance and portability of optoelectronic sensing systems.展开更多
基金This work was finanially supported by the Key Research Project of Jiangsu Province(No.BE2017645)Scientifc Research and Innovation Project for Graduate Students in Jiangsu Province(No.KYCX19-1757)。and a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions of China。
文摘A rigid aromatic diamine monomer containing di-tert-butylbenzene and dimethyl groups,3,3'-dimethyl-4,4'-diaminophenyl-3",5"-di-tert-butyltoluene,was successfully synthesized by a simple coupling reaction using 3,5-di-tert-butylbenzaldehyde and o-toluidine as starting materials.A series of novel polyimides(PI 3a-3c)with large pendant groups were prepared with the obtained diamine monomer and three different commercial aromatic dianhydrides(3,3',4,4'-biphenyltetracarboxylic dianhydride,4,4'-oxydiphthalic anhydride,and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride)by one-step high temperature polycondensation.The prepared polyimides exhibited high solubility and good membrane forming ability:they could be dissolved not only in some high boiling solvents such as DMF,NMP,DMAc,and m-Cresol at room temperature,but also in some low boiling solvents such as CHCl3,CH2Cl2,and THF.Their solubility in most solvents could exceed 10 wt%,and the flexible membranes could be obtained by casting their solutions.The prepared membranes exhibited good gas separation properties.The permeability coefficients of PI 3c for CO2 and O2 were up to 124.6 and 42.8 barrer,respectively,and the selectivity coefficients for CO2/CH4 and O2/N2 were 14.7 and 3.3,respectively.The membranes had light color and good optical transmission.Their optical transmittance at 450 nm wavelength was in the range of 67%-79%,and the cutoff wavelength was in the range of 310-348 nm.They also had good thermal properties with glass transition temperature(Tg)values in the range of 264-302℃.In addition,these membranes possessed good mechanical properties with tensile strength ranging between 77.8-87.4 MPa,initial modulus ranging between 1.69-1.82 GPa,and elongation at break ranging between 4.8%-6.1%.
基金Project supported by National Natural Science Foundation of China (Grant Nos. 10674060,10874043 and 10974181)by the National Basic Research Program of China (Grant Nos. 2005CB724508 and 2006CB921104)
文摘We study the ultraslow optical solitons in a resonant three-level atomic system via electromagnetically induced transparency under a density-matrix （DM） approach. The results of linear and nonlinear optical properties are compared with those obtained by using an amplitude variable （AV） approach. It is found that the results for both approaches are the same in the linear regime if the corresponding relations between the population-coherence decay rates in the DM approach and the energy-level decay rates in the AV approach are appropriately imposed. However, in the nonlinear regime there is a small difference for the self-phase modulation coefficient of the nonlinear SchrSdinger equation that governs the time evolution of probe pulse envelope. All analytical predicts are checked by numerical simulations.
基金supported by State Grid science and Technology Project(Grant No.5700-202127198A-0-0-00)。
文摘Optical nanofiber(ONF)is a special tool to achieve the interaction between light and matter with ultralow power.In this paper,we demonstrate V-type electromagnetically induced transparency(EIT)in cold atoms trapped by an ONFbased two-color optical lattice.At an optical depth of 7.35,90%transmission can be achieved by only 7.7 pW coupling power.The EIT peak and linewidth are investigated as a function of the coupling optical power.By modulating the pWlevel control beam of the ONF-EIT system in sequence,we further achieve efficient and high contrast control of the probe transmission,as well as its potential application in the field of quantum communication and quantum information science by using one-dimensional atomic chains.
基金Project supported by the National Natural Science Foundation of China(Grant No.11574188)the Project for Excellent Research Team of the National Natural Science Foundation of China(Grant No.61121064)
文摘A kind of photonic crystal structure with modulation of the refractive index is investigated both experimentally and theoretically for exploiting electromagnetically induced transparency（EIT）.The combination of EIT with periodically modulated refractive index medium gives rise to high efficiency reflection as well as forbidden transmission in a threelevel atomic system coupled by standing wave.We show an accurate theoretical simulation via transfer-matrix theory,automatically accounting for multilayer reflections,thus fully demonstrate the existence of photonic crystal structure in atomic vapor.
基金Project supported by the Key Science and Technology Research Project of Henan Province,China(Grant Nos.162102210164 and 1721023100107)the Natural Science Foundation of Henan Educational Committee,China(Grant No.17A140002)
文摘A graphene-based metamaterial for THz plasmon induced transparency(PIT) is presented and numerically studied in this paper, which consists of two horizontal graphene strips attached to a continuous vertical wire separately. The calculated surface current distributions demonstrate that the distinct PIT window results from the near-field coupling of two bright modes. To explore the physical mechanism of PIT effect, we employ the coupled Lorentz oscillator model. The transmission spectra obtained with this model fits well with the simulation results. The performance of the PIT system can be controlled through the geometry parameters of graphene strips. Moreover, the transparency window can be dynamically tuned by varying the Fermi energy and the carrier mobility of the graphene strips. The slow light effect is also explored in our proposed structure and it can achieve 1.25 ps when Fermi energy is 1.3 eV. Finally, the position of the transmission window with the variation of the nearby medium refractive index is examined. Such a proposed graphene-based PIT system may have great potential applications in photonic devices.
文摘In the face of deteriorating environmental conditions in the world,water quality control is an urgent task.It can be solved by creating sensors with high accuracy and low cost,which requires the development of fundamentally new radiophysical methods that take advantage of the optical,microwave and millimeter wavelengths that have a significantly greater sensitivity to low concentrations of pollutants and a lower inertia.The article presents prototypes of measuring cells of the microwave and optical ranges as well as the results of an experimental study of water of various degrees of pollution with their help.The results show that the use of the highly sensitive method of capillary-waveguide resonance makes it possible to detect the presence of micro impurities in water with concentrations up to0.1%and to identify water even from sources of various natural origins.In addition,the use of measurements at several frequencies in the optical range will make it possible to solve the problem of creating water control sensors with high sensitivity to pollution and low cost.It can be concluded that the possibility of complex use of multiwave sensors(optical,infrared and microwave ranges)allows to increase the sensitivity and reliability of water quality assessment.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10647132)the Science Foundation from the Education Department of Hunan Province,China (Grant No. 10A100)
文摘An approach for solving the excitonic absorption in a semiconductor quantum well driven by an intense terahertz field is presented.The formalism relies on the stationary single-photon Schro¨dinger equation in the full quantum mechanical framework.The optical absorption dynamics in both weak and strong couplings are discussed and compared.The excitonic absorption spectra show the Autler-Townes doublets for the resonance terahertz field,a replica peak for the non-resonance terahertz field,and the electromagnetically induced transparency phenomenon for modulating the decay rate of the second electron state in the weak coupling.In particular,the electromagnetically induced transparency phenomenon window range is discussed.In the strong coupling region,the multi-order energy level resonance splitting due to the strong optical field is found.There are three（non-resonance terahertz field） or four（resonance terahertz field） peaks in the optical absorption spectra.This work provides a simple and convenient approach to deal with the optical absorption in the exciton system.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0304203)the National Natural Science Foundation of China(Grant Nos.61675120,11434007,and 61875110)+2 种基金Project of the National Natural Science Foundation of China for Excellent Research Team(Grant No.61121064)the Shanxi “1331 Project” Key Subjects Construction,PCSIRT,China(Grant No.IRT_17R70)the 111 Project,China(Grant No.D18001)
文摘Optical nanofiber(ONF) is a special tool for effectively controlling coupling of light and atoms. In this paper, we study the ladder-type electromagnetically induced transparent(EIT) under ultralow power level in a warm cesium vapor by observing the transmission of ONF that couples the 6 S → 6 P Cs atoms in the presence of a 6 P → 8 S control beam through the same fiber. The linewidth and transmission of the EIT signal are investigated at different intensities of the control laser. In addition, we theoretically study the nonlinear interaction at the ONF interface using the multi-level density matrix equations, and obtain good agreements between theory and experiments. The results may have great significance for further study of optical nonlinear effect at low power level.
基金partially supported by the National Natural Science Foundation of China (Grant Nos. 61078051,60978017,10974125 and 60821004)the NCET Project from the Education Ministry of China (Grant No. NCET-07-0524)the Specialized Research Fund for the Doctoral Program of China (Grant No. 20070108003)
文摘In a Doppler-broadened ladder-type cesium atomic system （6S1/2 6P3/2-8S1/2）, this paper characterizes electro- magnetically induced transparency （EIT） in two different experimental arrangements, and investigates the influence of the double-resonance optical-pumping （DROP） effect on EIT in both arrangements. When the probe laser is weak, DROP is explicitly suppressed. When the probe laser is moderate, population of the intermediate level （6P3/2 FI = 5） is remarkable, therefore DROP is mixed with EIT. An interesting bimodal spectrum with the broad component due to DROP and the narrow part due to EIT has been clearly observed in cesium 6S1/2 F = 4-6P3/2 F^1= 5-8S1/2 F^11 = 4 transitions.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11274148 and 10704031)the Basic Scientific Research Business Expenses of the Central University,China (Grant No. lzujbky-2010-75)the Open Project of Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education,Lanzhou University,China
文摘We study the features of electromagnetically induced transparency（EIT） in a single Λ-type three-level atom placed in a high-finesse cavity under the action of a coupling laser and a probe laser.Our calculations show that three transparency windows appear when the pump strength is large enough.This can be explained by the residual pump in the cavity mostly resulting in energy splitting.The level ｜3 is split into four slightly different energy levels,and interference takes place between the excitation pathways.Furthermore,it is also shown that the frequencies of the EIT windows can be tuned by changing the coupling field detuning 2,and that the reflection profile is very sensitive to the cavity field detuning △c.
基金The project supported by National Fundamental Research Program of China under Grant No.2001CB309310National Natural Science Foundation of China under Grant Nos.90103026,10125419,and 10121503
文摘In this paper, we propose and analyze an optical multi-wave mixing scheme for the generation of coherent light in a five-level atomic system in the context of electromagnetically induced transparency. A detailed semiclassical study of the propagation of generated mixing and probe fields is demonstrated. The analytical dependence of the generated mixing field on the probe field and the respective detuning is predicted. Such a nonlinear optical process can be used for generating short-wavelength radiation at low pump intensities.
基金supported by the National Natural Science Foundation of China(Grant Nos.11304387 and 61205108)
文摘We theoretically investigate an enhanced electromagnetically induced transparency （EIT） cooling method by introduc- ing a high finesse cavity. We find that the quantum destructive interference that is induced by the EIT effect and the cavity coupling can eliminate all of the heating effects in the cooling process by choosing appropriate parameters. Compared with the EIT cooling scheme, a lower final temperature can be obtained under the same conditions in our scheme.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11104185,11174084,10934011 and 61378060the National Basic Research Program of China under Grant No 2012CB921904+2 种基金the Innovation Program of Shanghai Municipal Education Commission under Grant No 11YZ118the Shanghai Dawn Project of Shanghai Education Commission under Grant No11SG44the Hujiang Foundation of China under Grant No B14004
文摘According to density matrix equations of the interaction between light and matter, the expression for the suscep- tibility of the Eu^3＋ ：Y2SiO5 crystal is obtained. When the control field is a Gaussian beam, we investigate and analyze the influence of probe detuning, the Rabi frequency of the control field and the laser line width on the transverse optical properties. We also analyze the influence of the dope-ion concentration on electromagnetieally induced transparency （EIT）. The analysis result indicates that the transmission is not a monotonic function of the dope-ion concentration. Based on the influences of various parameters on the transverse optical properties, we choose the appropriate parameters to realize the desired EIT and gradient refractive index, which has applications in focusing and imaging.
文摘Optical microscopy,optical transmission spectra,sweep electron microscope,electron microprobe analysis etc.were used to study the appearance and machanism of formation of the defects caused by impurities which seriously affect the optical transparency of doped bismuth germanate.The methods of improving the optical transparency were also discussed.
基金supported by the National Natural Science Foundation of China (Grant No. 12104227)the Scientific Research Foundation of Nanjing Institute of Technology (Grant No. YKJ202021)the Guizhou Provincial Science and Technology Projects (Grant No. ZK [2022] general 035)。
文摘We show that an optical transparency can be obtained by using only one single magneto-optical ring resonator. This effect is based on the splitting of counterclockwise and clockwise modes in the ring resonator. Within a proposed resonator-waveguide configuration the superposition between the two degeneracy broken modes produces a transparency window,which can be closed, open, and modified by tuning the applied magnetic field. This phenomenon is an analogue of Autler–Townes splitting, and the magnetic field is equivalent to the strong external pump field. We provide a theoretic analysis on the induced transparency, and numerically demonstrate the effect using full-wave simulation. Feasible implication of this effect and its potential applications are also discussed.
文摘BACKGROUND Atypical optic neuritis,consisting of neuromyelitis optica spectrum disorders(NMOSD)or myelin oligodendrocyte glycoprotein antibody disease(MOGAD),has a very similar presentation but different prognostic implications and longterm management strategies.Vascular and metabolic factors are being thought to play a role in such autoimmune neuro-inflammatory disorders,apart from the obvious immune mediated damage.With the advent of optical coherence tomography angiography(OCTA),it is easy to pick up on these subclinical macular microvascular and structural changes.AIM To study the macular microvascular and structural changes on OCTA in atypical optic neuritis.METHODS This observational cross-sectional study involved 8 NMOSD and 17 MOGAD patients,diagnosed serologically,as well as 10 healthy controls.Macular vascular density(MVD)and ganglion cell+inner plexiform layer thickness(GCIPL)were studied using OCTA.RESULTS There was a significant reduction in MVD in NMOSD and MOGAD affected as well as unaffected eyes when compared with healthy controls.NMOSD and MOGAD affected eyes had significant GCIPL thinning compared with healthy controls.NMOSD unaffected eyes did not show significant GCIPL thinning compared to healthy controls in contrast to MOGAD unaffected eyes.On comparing NMOSD with MOGAD,there was no significant difference in terms of MVD or GCIPL in the affected or unaffected eyes.CONCLUSION Although significant microvascular and structural changes are present on OCTA between atypical optic neuritis and normal patients,they could not help in differentiating between NMOSD and MOGAD cases.
基金financially supported by the National Natural Science Foundation of China(Grant No.11872344)the Innovatory Development Foundation of the China Academy of Engineering Physics(Grant No.CX20210026).
文摘Over the past several decades,much research effort has been dedicated to the study of optical windows,with two primary themes emerging as key focuses.The first of these centers on investigating the optical properties of typical transparent single crystals under shock or ramp compression,which helps in the selection of appropriate optical windows for high-pressure experiments.The second involves the exploration of novel optical windows,particularly transparent polycrystalline ceramics,which not only match the shock impedance of the samples,but also preserve transparency under dynamic compression.In this study,we first integrate existing research on the evolution of optical properties in transparent single crystals and polycrystalline ceramics subjected to shock or ramp loading,proposing a mechanism that links mesoscopic damage to macroscopic optical transparency.Subsequently,through a systematic integration of experiments and computational analyses on polycrystalline transparent ceramics,we demonstrate that shock transparency can be enhanced by optimizing grain size and that shock impedance can be designed via compositional tuning.Notably,our results reveal that nano-grained MgAl_(2)O_(4) ceramics exhibit outstanding optical transparency under high shock pressures,highlighting a promising strategy for designing optical windows that retain transparency under extreme dynamic loading conditions.
基金supports from the National Key Research and Development Program of China(2023YFB2806803)the National Natural Science Foundation of China(62075127).
文摘Liquid crystal Pacharatnam-Berry phase optical elements(PBOEs)have found promising applications in augmented reality and virtual reality because of their slim formfactor,lightweight,and high optical efficiency.However,chromatic aberration remains a serious longstanding problem for diffractive optics,hindering their broader adoption.To overcome the chromatic aberrations for red,green and blue(RGB)light sources,in this paper,we propose a counterintuitive multi-twist structure to achieve narrowband PBOEs without crosstalk,which plays a vital role to eliminate the chromatic aberration.The performance of our designed and fabricated narrowband Pacharatnam-Berry lenses(PBLs)aligns well with our simulation results.Furthermore,in a feasibility demonstration experiment using a laser projector,our proposed PBL system indeed exhibits a diminished chromatic aberration as compared to a broadband PBL.Additionally,polarization raytracing is implemented to demonstrate the versatility of the multi-twist structure for designing any RGB wavelengths with high contrast ratios.This analysis explores the feasibility of using RGB laser lines and quantum dot light-emitting diodes.Overall,our approach enables high optical efficiency,low fabrication complexity,and high degree of design freedom to accommodate any liquid crystal material and RGB light sources,holding immense potential for widespread applications of achromatic PBOEs.
文摘Optical network-on-chip(ONoC) systems have emerged as a promising solution to overcome limitations of traditional electronic interconnects. Efficient ONoC architectures rely on optical routers, enabling high-speed data transfer, efficient routing, and scalability. This paper presents a comprehensive survey analyzing optical router designs, specifically microring resonators(MRRs), Mach-Zehnder interferometers(MZIs), and hybrid architectures. Selected comparison criteria, chosen for their critical importance, significantly impact router functionality and performance. By emphasizing these criteria, valuable insights into the strengths and limitations of different designs are gained, facilitating informed decisions and advancements in optical networking. While other factors contribute to performance and efficiency, the chosen criteria consistently address fundamental elements, enabling meaningful evaluation. This work serves as a valuable resource for beginners, providing a solid foundation in understanding ONoC and optical routers. It also offers an in-depth survey for experts, laying the groundwork for further exploration. Additionally, the importance of considering design constraints and requirements when selecting an optimal router design is highlighted. Continued research and innovation will enable the development of efficient optical router solutions that meet the evolving needs of modern computing systems. This survey underscores the significance of ongoing advancements in the field and their potential impact on future technologies.
基金financial supports from National Natural Science Foundation of China(62175023).
文摘In this study,we developed a single-beam optical trap-based surface-enhanced Raman scattering(SERS)optofluidic molecular fingerprint spectroscopy detection system.This system utilizes a single-beam optical trap to concentrate free silver nanoparticles(AgNPs)within an optofluidic chip,significantly enhancing SERS performance.We investigated the optical field distribution characteristics within the tapered fiber using COMSOL simulation software and established a MATLAB simulation model to validate the single-beam optical trap's effectiveness in capturing AgNPs,demonstrating the theoretical feasibility of our approach.To verify the particle capture efficacy of the system,we experimentally controlled the optical trap's on-off state to manage the capture and release of particles precisely.The experimental results indicated that the Raman signal intensity in the capture state was significantly higher than in the non-capture state,confirming that the single-beam optical trap effectively enhances the SERS detection capability of the optofluidic detection system.Furthermore,we employed Raman mapping techniques to investigate the impact of the capture area on the SERS effect,revealing that the spectral intensity of molecular fingerprints in the laser-trapping region is significantly improved.We successfully detected the Raman spectrum of crystal violet at a concentration of 10^(−9)mol/L and pesticide thiram at a concentration of 10^(−5)mol/L,further demonstrating the ability of the single-beam optical trap in enhancing the molecular fingerprint spectrum identification capability of the SERS optofluidic chips.The optical trapping SERS optofluidic detection system developed in this study,as a key component of an integrated optoelectronic sensing system,holds the potential for integration with portable high-power lasers and high-performance Raman spectrometers.This integration is expected to advance highly integrated technologies and significantly enhance the overall performance and portability of optoelectronic sensing systems.
