Microwave magneto-optic （MO） modulators can directly transform radio frequency （RF） signals into optical data through the Bragg diffraction of guided optical waves （GOWs） induced by microwave magneto-static wav...Microwave magneto-optic （MO） modulators can directly transform radio frequency （RF） signals into optical data through the Bragg diffraction of guided optical waves （GOWs） induced by microwave magneto-static waves （MSWs）. According to the MO coupled-mode theory, the modulation of continuous GOWs by a rectangular magneto-static-forwardvolume-wave （MSFVW） pulse in MO film waveguide is studied in the small signal case and the modulated optical pulse at the output is analyzed by means of an analytical form, which is dependent on the instantaneous diffraction intensity determined by the overlap of rectangular MSFVW pulse and light beam aperture. On the basis of it, the characteristics of MSFVW-based MO modulators can be explained well for the case of rectangular pulse modulation. It is also shown that the line codes of optical data generated by MO Bragg modulators can be controlled by adjusting the duty factor of modulating pulse signals.展开更多
In current investigations of electric arc plasmas, experiments based on modern testing technology play an important role. To enrich the testing methods and contribute to the understanding and grasping of the inherent ...In current investigations of electric arc plasmas, experiments based on modern testing technology play an important role. To enrich the testing methods and contribute to the understanding and grasping of the inherent mechanism of air switching arcs, in this paper, a nonintrusive detecting system is described that combines the magneto-optic imaging（MOI） technique with the solution to inverse electromagnetic problems. The detecting system works in a sequence of main steps as follows： MOI of the variation of the arc flux density over a plane, magnetic field information extracted from the magneto-optic（MO） images, arc current density distribution and spatial pattern reconstruction by inverting the resulting field data. Correspondingly, in the system, an MOI set-up is designed based on the Faraday effect and the polarization properties of light, and an intelligent inversion algorithm is proposed that involves simulated annealing（SA）.Experiments were carried out for high current（2 kA RMS） discharge cases in a typical low-voltage switchgear. The results show that the MO detection system possesses the advantages of visualization, high resolution and response, and electrical insulation, which provides a novel diagnostics tool for further studies of the arc.展开更多
We introduce a nanoplasmonic isolator that consists of a cylindrical resonator placed close to a metal-dielectric-metal(MDM) waveguide. The material filling the waveguide and resonator is a magneto-optical(MO) materia...We introduce a nanoplasmonic isolator that consists of a cylindrical resonator placed close to a metal-dielectric-metal(MDM) waveguide. The material filling the waveguide and resonator is a magneto-optical(MO) material, and the structure is under an externally applied static magnetic field. We theoretically investigate the properties of the structure and show that the cavity mode without MO activity splits into two modes when the MO activity is present. In addition, we find that the presence of the MDM waveguide leads to a second resonance due to the geometrical asymmetry caused by the existence of the waveguide. We also show that, when MO activity is present, the cavity becomes a traveling wave resonator. Thus, the transmission of the structure depends on the direction of the incident light, and the proposed structure operates as an optical isolator.展开更多
Magnetic fluid is a kind of functional composite material with nanosized structure and unique optical properties. The tunable magneto-optic modulation of magnetic fluid under external magnetic field, achieved by adjus...Magnetic fluid is a kind of functional composite material with nanosized structure and unique optical properties. The tunable magneto-optic modulation of magnetic fluid under external magnetic field, achieved by adjusting the polarization direction of incident light, is investigated theoretically and experimentally in this work. The corresponding modulation depth and response time are obtained. The accompanying mechanisms are clarified by using the theory of dichroism of magtietic fluid and the aggregation/disintegration processes of magnetic particles within magnetic fluid when the external magnetic field turns on/off.展开更多
The polarization of a D-shaped fiber is modulated after immersing it in magnetic fluid(MF)and applying a magnetic field.Theoretical analysis predicts that magneto-optical dichroism of MF plays a key role in light pola...The polarization of a D-shaped fiber is modulated after immersing it in magnetic fluid(MF)and applying a magnetic field.Theoretical analysis predicts that magneto-optical dichroism of MF plays a key role in light polarization modulation.During light polarization modulation,the evanescent wave polarized parallel to the magnetic field has greater loss than its orthogonal component.Light polarization of a D-shaped fiber with a wide polished surface can be modulated easily.High concentration MF and a large magnetic field all have great ability to modulate light polarization.展开更多
Latent fingerprints are extremely vital for personal identification and criminalinvestigation,and potential information recognition techniques have been widelyused in the fields of information and communication electr...Latent fingerprints are extremely vital for personal identification and criminalinvestigation,and potential information recognition techniques have been widelyused in the fields of information and communication electronics.Although physicalpowder dusting methods have been frequently employed to develop latent fingerprintsand most of them are carried out by using single component powders ofmicron-sized fluorescent particles,magnetic powders,or metal particles,there isstill an enormous challenge in producing high-resolution image of latent fingerprintsat different backgrounds or substrates.Herein,a novel and effectivenanoimpregnation method is developed to synthesize bifunctional magnetic fluorescentmesoporous microspheres for latent fingerprints visualization by growthof mesoporous silica(mesoSiO_(2))on magical Fe_(3)O_(4) core and then deposition offluorescent YVO4:Eu^(3+)nanoparticles in the mesopores.The obtainedFe_(3)O_(4)@mesoSiO_(2)@YVO4:Eu^(3+)microspheres possess spatially isolated magneticcore and fluorescent shell which were insulated by mesoporous silica layer.Dueto their small particle size of submicrometer scale,high magnetization and lowmagnetic remanence as well as the combined magnetic and fluorescent properties,the microspheres show superior performance in visual latent fingerprint recognitionwith high contrast,high anti-interference,and sensitivity as well as goodretention on multifarious substrates regardless of surface permeability,roughness,refraction,colorfulness,and background fluorescence interference,and it makesthem ideal candidates for practical application in fingerprint visualization andeven magneto-optic information storage.展开更多
The magnetization reversal process of Fe/MgO （001） thin film is investigated by combining transverse and longi- tudinal hysteresis loops. Owing to the competition between domain wall pinning energy and weak uniaxial...The magnetization reversal process of Fe/MgO （001） thin film is investigated by combining transverse and longi- tudinal hysteresis loops. Owing to the competition between domain wall pinning energy and weak uniaxial magnetic anisotropy, the typical magnetization reversal process of Fe ultrathin film can take place via either an ＂l-jump＂ process near the easy axis, or a ＂2-jump＂ process near the hard axis, depending on the applied field orientation. Besides, the hysteresis loop presents strong asymmetry resulting from the variation of the detected light intensity due to the quadratic magneto-optic effect. Furthermore, we modify the detectable light intensity formula and simulate the hysteresis loops of the Kerr signal. The results show that they are in good agreement with the experimental data.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
Aiming at the approximate measurement of magnetic rotation angle in optical current sensor based on light intensity detection mode,this paper proposes a current measurement method based on triangular constant transfor...Aiming at the approximate measurement of magnetic rotation angle in optical current sensor based on light intensity detection mode,this paper proposes a current measurement method based on triangular constant transformation to reconstruct magnetic rotation angle,so as to avoid the large current measurement error caused by the approximate measurement of the magnetic rotation angle.By extracting the direct current(DC)component and the alternating current(AC)component of the light intensity signal detected by the photoelectric detector(PD),the sine signal containing the magnetic rotation angle is directly obtained by dividing the two components,and then the triangular identity transformation method is used to linearly demodulate the magnetic rotation angle and reconstruct the current waveform.The experimental results show that the relative error of current measurement does not exceed 1.40%in the current range of 0.05—0.50 A,which is less than the approximate linear measurement(ALM)method,and the magnetic rotation angle and the current have a good linear relationship.展开更多
Magneto-optic(MO)coupling of guided optical waves with microwave magnetostatic waves(MSWs)simultaneously excited by multiple radio frequency(RF)signals can lead to multifrequency diffraction effects and then parallel ...Magneto-optic(MO)coupling of guided optical waves with microwave magnetostatic waves(MSWs)simultaneously excited by multiple radio frequency(RF)signals can lead to multifrequency diffraction effects and then parallel processing of RF signals can be realized by using of the characteristics that diffraction efficiencies(DEs)are approximately in direct proportion to RF signals intensities and diffraction angles are related to frequencies of the corresponding RF signals within linear MO interaction region.In this paper,studied is the multifrequency MO Bragg diffraction in first-order MO interaction approximation,and obtained was the approximate analytical expression for principle diffraction efficiency(PDE).Also,put forward was a parallel imaging method of relative intensity of RF signals based on single-frequency diffraction.By calculation and analysis,it is shown that the relative error is not more than 0.3dB for the case of three RF signals within the frequency space of 60MHz.展开更多
This paper presents the growth of cerium substituted YIG (Ce1 YIG) thin films on silica substrate.The large Faraday rotation coefficient and strong in-plane anisotropy were observed. The film is desirable for waveguid...This paper presents the growth of cerium substituted YIG (Ce1 YIG) thin films on silica substrate.The large Faraday rotation coefficient and strong in-plane anisotropy were observed. The film is desirable for waveguide configuration isolator application.展开更多
We propose a uniform backfire-to-endfire leaky-wave antenna(LWA)based on a topological one-way waveguide under external bias magnetic field.We systematically analyze the dispersion,showing that the proposed structure ...We propose a uniform backfire-to-endfire leaky-wave antenna(LWA)based on a topological one-way waveguide under external bias magnetic field.We systematically analyze the dispersion,showing that the proposed structure supports leaky mode arisen from total internal reflection.By means of tuning frequency or magnetic field,we obtain fixed-bias frequency and fixed-frequency bias LWA with continuous beam scanning from backward,broadside to forward direction.More importantly,we,for the first time,demonstrate that this proposed LWA shows mechanical tunability,allowing us to manipulate the radiation direction from backward,broadside to forward direction by mechanically tuning the air layer thickness.The simulated results show that our system exhibits super low 3dB beam width,high radiation efficiency as well as high antenna gain.Being provided such multiple controlled(especially mechanically)beam scanning manners,the present LWA paves an advanced approach for continuous beam scanning,holding a great potential for applications in modern communication and radar system.展开更多
基金supported by the National Natural Science Foundation of China under Grant No 60671027the Application Basis Research Foundation of Sichuan Province under Grant No 07JY029-089
文摘Microwave magneto-optic （MO） modulators can directly transform radio frequency （RF） signals into optical data through the Bragg diffraction of guided optical waves （GOWs） induced by microwave magneto-static waves （MSWs）. According to the MO coupled-mode theory, the modulation of continuous GOWs by a rectangular magneto-static-forwardvolume-wave （MSFVW） pulse in MO film waveguide is studied in the small signal case and the modulated optical pulse at the output is analyzed by means of an analytical form, which is dependent on the instantaneous diffraction intensity determined by the overlap of rectangular MSFVW pulse and light beam aperture. On the basis of it, the characteristics of MSFVW-based MO modulators can be explained well for the case of rectangular pulse modulation. It is also shown that the line codes of optical data generated by MO Bragg modulators can be controlled by adjusting the duty factor of modulating pulse signals.
基金supported by the Fundamental Research Funds for the Central Universities of China(XJJ2011019)
文摘In current investigations of electric arc plasmas, experiments based on modern testing technology play an important role. To enrich the testing methods and contribute to the understanding and grasping of the inherent mechanism of air switching arcs, in this paper, a nonintrusive detecting system is described that combines the magneto-optic imaging（MOI） technique with the solution to inverse electromagnetic problems. The detecting system works in a sequence of main steps as follows： MOI of the variation of the arc flux density over a plane, magnetic field information extracted from the magneto-optic（MO） images, arc current density distribution and spatial pattern reconstruction by inverting the resulting field data. Correspondingly, in the system, an MOI set-up is designed based on the Faraday effect and the polarization properties of light, and an intelligent inversion algorithm is proposed that involves simulated annealing（SA）.Experiments were carried out for high current（2 kA RMS） discharge cases in a typical low-voltage switchgear. The results show that the MO detection system possesses the advantages of visualization, high resolution and response, and electrical insulation, which provides a novel diagnostics tool for further studies of the arc.
文摘We introduce a nanoplasmonic isolator that consists of a cylindrical resonator placed close to a metal-dielectric-metal(MDM) waveguide. The material filling the waveguide and resonator is a magneto-optical(MO) material, and the structure is under an externally applied static magnetic field. We theoretically investigate the properties of the structure and show that the cavity mode without MO activity splits into two modes when the MO activity is present. In addition, we find that the presence of the MDM waveguide leads to a second resonance due to the geometrical asymmetry caused by the existence of the waveguide. We also show that, when MO activity is present, the cavity becomes a traveling wave resonator. Thus, the transmission of the structure depends on the direction of the incident light, and the proposed structure operates as an optical isolator.
基金supported by the National Natural Science Foundation of China (Grant No. 10704048)the Innovation Program of Shanghai Municipal Education Commission, China (Grant No. 11YZ120)the Innovation Fund Project for Graduate Student of Shanghai, China (Grant No. JWCXSL1022)
文摘Magnetic fluid is a kind of functional composite material with nanosized structure and unique optical properties. The tunable magneto-optic modulation of magnetic fluid under external magnetic field, achieved by adjusting the polarization direction of incident light, is investigated theoretically and experimentally in this work. The corresponding modulation depth and response time are obtained. The accompanying mechanisms are clarified by using the theory of dichroism of magtietic fluid and the aggregation/disintegration processes of magnetic particles within magnetic fluid when the external magnetic field turns on/off.
基金supported by the National Natural Science Foundation of China(Nos.61675115 and 11574178)the Shandong Provincial Natural Science Foundation(No.ZR2016JL005)。
文摘The polarization of a D-shaped fiber is modulated after immersing it in magnetic fluid(MF)and applying a magnetic field.Theoretical analysis predicts that magneto-optical dichroism of MF plays a key role in light polarization modulation.During light polarization modulation,the evanescent wave polarized parallel to the magnetic field has greater loss than its orthogonal component.Light polarization of a D-shaped fiber with a wide polished surface can be modulated easily.High concentration MF and a large magnetic field all have great ability to modulate light polarization.
基金China Postdoctoral Science Foundation,Grant/Award Numbers:2021M690660,2021TQ0066Key Basic Research Program of Science and Technology Commission of Shanghai Municipality,Grant/Award Number:20JC1415300+1 种基金National Natural Science Foundation of China,Grant/Award Numbers:21701153,21875044Program of Shanghai Academic Research Leader,Grant/Award Number:19XD1420300。
文摘Latent fingerprints are extremely vital for personal identification and criminalinvestigation,and potential information recognition techniques have been widelyused in the fields of information and communication electronics.Although physicalpowder dusting methods have been frequently employed to develop latent fingerprintsand most of them are carried out by using single component powders ofmicron-sized fluorescent particles,magnetic powders,or metal particles,there isstill an enormous challenge in producing high-resolution image of latent fingerprintsat different backgrounds or substrates.Herein,a novel and effectivenanoimpregnation method is developed to synthesize bifunctional magnetic fluorescentmesoporous microspheres for latent fingerprints visualization by growthof mesoporous silica(mesoSiO_(2))on magical Fe_(3)O_(4) core and then deposition offluorescent YVO4:Eu^(3+)nanoparticles in the mesopores.The obtainedFe_(3)O_(4)@mesoSiO_(2)@YVO4:Eu^(3+)microspheres possess spatially isolated magneticcore and fluorescent shell which were insulated by mesoporous silica layer.Dueto their small particle size of submicrometer scale,high magnetization and lowmagnetic remanence as well as the combined magnetic and fluorescent properties,the microspheres show superior performance in visual latent fingerprint recognitionwith high contrast,high anti-interference,and sensitivity as well as goodretention on multifarious substrates regardless of surface permeability,roughness,refraction,colorfulness,and background fluorescence interference,and it makesthem ideal candidates for practical application in fingerprint visualization andeven magneto-optic information storage.
基金supported by the National Natural Science Foundation of China(Grant Nos.11274033,11474015,and 61227902)the Research Fund for the Doctoral Program of Higher Education of China(Grant No.20131102130005)the Beijing Key Discipline Foundation of Condensed Matter Physics
文摘The magnetization reversal process of Fe/MgO （001） thin film is investigated by combining transverse and longi- tudinal hysteresis loops. Owing to the competition between domain wall pinning energy and weak uniaxial magnetic anisotropy, the typical magnetization reversal process of Fe ultrathin film can take place via either an ＂l-jump＂ process near the easy axis, or a ＂2-jump＂ process near the hard axis, depending on the applied field orientation. Besides, the hysteresis loop presents strong asymmetry resulting from the variation of the detected light intensity due to the quadratic magneto-optic effect. Furthermore, we modify the detectable light intensity formula and simulate the hysteresis loops of the Kerr signal. The results show that they are in good agreement with the experimental data.
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.
基金the Joint Guidance Project of Natural Science Foundation of Heilongjiang Province(No.LH2021F008)。
文摘Aiming at the approximate measurement of magnetic rotation angle in optical current sensor based on light intensity detection mode,this paper proposes a current measurement method based on triangular constant transformation to reconstruct magnetic rotation angle,so as to avoid the large current measurement error caused by the approximate measurement of the magnetic rotation angle.By extracting the direct current(DC)component and the alternating current(AC)component of the light intensity signal detected by the photoelectric detector(PD),the sine signal containing the magnetic rotation angle is directly obtained by dividing the two components,and then the triangular identity transformation method is used to linearly demodulate the magnetic rotation angle and reconstruct the current waveform.The experimental results show that the relative error of current measurement does not exceed 1.40%in the current range of 0.05—0.50 A,which is less than the approximate linear measurement(ALM)method,and the magnetic rotation angle and the current have a good linear relationship.
基金National Natural Science Foundation of China(60671027)Sichuan Province Basic Research Project(07JY029-089)
文摘Magneto-optic(MO)coupling of guided optical waves with microwave magnetostatic waves(MSWs)simultaneously excited by multiple radio frequency(RF)signals can lead to multifrequency diffraction effects and then parallel processing of RF signals can be realized by using of the characteristics that diffraction efficiencies(DEs)are approximately in direct proportion to RF signals intensities and diffraction angles are related to frequencies of the corresponding RF signals within linear MO interaction region.In this paper,studied is the multifrequency MO Bragg diffraction in first-order MO interaction approximation,and obtained was the approximate analytical expression for principle diffraction efficiency(PDE).Also,put forward was a parallel imaging method of relative intensity of RF signals based on single-frequency diffraction.By calculation and analysis,it is shown that the relative error is not more than 0.3dB for the case of three RF signals within the frequency space of 60MHz.
文摘This paper presents the growth of cerium substituted YIG (Ce1 YIG) thin films on silica substrate.The large Faraday rotation coefficient and strong in-plane anisotropy were observed. The film is desirable for waveguide configuration isolator application.
基金This work was supported by the National Natural Science Foundation of China(NSFC)(Grant No.61372005)the National Natural Science Foundation of China(NSFC)under the key project(Grant No.41331070)+1 种基金the Natural Science Foundation of Ningbo(No.2019A610081)Zhejiang Provincial Natural Science Foundation of China(No.LY20F050006).
文摘We propose a uniform backfire-to-endfire leaky-wave antenna(LWA)based on a topological one-way waveguide under external bias magnetic field.We systematically analyze the dispersion,showing that the proposed structure supports leaky mode arisen from total internal reflection.By means of tuning frequency or magnetic field,we obtain fixed-bias frequency and fixed-frequency bias LWA with continuous beam scanning from backward,broadside to forward direction.More importantly,we,for the first time,demonstrate that this proposed LWA shows mechanical tunability,allowing us to manipulate the radiation direction from backward,broadside to forward direction by mechanically tuning the air layer thickness.The simulated results show that our system exhibits super low 3dB beam width,high radiation efficiency as well as high antenna gain.Being provided such multiple controlled(especially mechanically)beam scanning manners,the present LWA paves an advanced approach for continuous beam scanning,holding a great potential for applications in modern communication and radar system.
