Based on Fabry model and finite-different time-domain(FDTD) method, the plasmonic structure composed of a metal-insulator-metal(MIM) bus waveguide and a side-coupled resonator was investigated. It is found that the tr...Based on Fabry model and finite-different time-domain(FDTD) method, the plasmonic structure composed of a metal-insulator-metal(MIM) bus waveguide and a side-coupled resonator was investigated. It is found that the transmission features can be regulated by the cavity width and coupling distance. Electromagnetically induced transparency(EIT)-like transmission can be excited by adding an identical resonator on the pre-existing structure. Combining the foregoing theoretical analysis with coupled mode theory(CMT), the formation process of the EIT-like transmission was detailedly analyzed. EIT-like transmission can also be excited in plasmonic structure with two detuned resonators. By altering the structure parameters, the transparency window can be purposefully modulated. With the merits of compact structure and simplicity in fabrication, the proposed structures may have a broad prospect of applications in highly integrated optical circuits.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
This paper proposes a new metamaterial design that can achieve electromagnetic induction transparency-like (EIT-like) effects in the microwave band. The unit structure of metamaterials consists of square rings and met...This paper proposes a new metamaterial design that can achieve electromagnetic induction transparency-like (EIT-like) effects in the microwave band. The unit structure of metamaterials consists of square rings and metal wires. The square ring acts as the “bright state” and the metal wire acts as the “dark state”. The destructive interference between the bright state and the dark state produces an EIT-like effect. In the simulation results, a transparent window centered at 4.00 GHz can be observed in the transmission spectrum. By studying the phase change of the transparent window, it is found that the group delay of the metamaterial structure can reach 0.39 ns at 4.00 GHz. This paper </span><span>also studies the influence of the refractive index of the medium on the</span><span> EIT-like effect. Numerical simulations show that such metamaterial is very sensitive to the refractive index of the medium, and the sensitivity is 15 mm/RIU. Our design can be extended to other frequency bands and may have potential applications in filtering, sensing, slow-light devices, and nonlinear optics.展开更多
We present an investigation of double-resonance optical pumping (DROP) spectra under the condition of single-photon frequency detuning based on a cesium 6S1/2-6P3/2-8S1/2 ladder-type system with a room-temperature v...We present an investigation of double-resonance optical pumping (DROP) spectra under the condition of single-photon frequency detuning based on a cesium 6S1/2-6P3/2-8S1/2 ladder-type system with a room-temperature vapor cell. Two DROP peaks are found, and their origins are explored. One peak has a narrow linewidth due to the atomic coherence for a counterpropagating configuration; the other peak has a broad linewidth, owing to the spontaneous decay for a coprop-agating configuration. This kind of off-resonant DROP spectrum can be used to control and offset-lock a laser frequency to a transition between excited states. We apply this technique to a multiphoton cesium magneto-optical trap, which can efficiently trap atoms on both red and blue sides of the two-photon resonance.展开更多
We show that it is possible to use a single sideband to induce two-photon transparency in a three-level cascade medium. The medium simultaneously absorbs two photons as a one-step process when the middle level is far ...We show that it is possible to use a single sideband to induce two-photon transparency in a three-level cascade medium. The medium simultaneously absorbs two photons as a one-step process when the middle level is far off one-photon resonance. A resonant sideband coupling on the upper transition and the two-photon one-step process drive the medium into a trapped state, and the dominant component is the ground state. Thus almost all population is trapped in the ground state and the two-photon absorption is dramatically suppressed. We present a numerical calculation for arbitrary values of the atomic and field parameters and also provide an analytic description for the required conditions.展开更多
The harmonics and resonance of traction power supply systems(TPSSs)aggravate the electromagnetic interference(EMI)to adjacent metallic pipelines(MPs),which has aroused widespread concern.In this paper,an evaluation me...The harmonics and resonance of traction power supply systems(TPSSs)aggravate the electromagnetic interference(EMI)to adjacent metallic pipelines(MPs),which has aroused widespread concern.In this paper,an evaluation method on pipeline interference voltage under harmonic induction is presented.The results show that the Carson integral formula is more accurate in calculating the mutual impedance at higher frequencies.Then,an integrated train-network-pipeline model is established to estimate the influences of harmonic distortion and resonance on an MP.It is revealed that the higher the harmonic cur-rent distortion rate of the traction load,the larger the interference voltage on an MP.Particularly,the interference voltage is amplified up to 7 times when the TPSS resonates,which is worthy of attention.In addition,the parameters that affect the variation and sensitivity of the interference voltage are studied,namely,the pipeline coating material,locomotive position,and soil resistivity,indicating that soil resistivity and 3PE(3-layer polyethylene)anticorrosive coating are more sensitive to harmonic induction.Field test results show that the harmonic distortion can make the interference voltage more serious,and the protective measures are optimized.展开更多
Metasurface analogue of the phenomenon of electromagnetically induced transparency(EIT)that is originally observed in atomic gases offers diverse applications for new photonic components such as nonlinear optical unit...Metasurface analogue of the phenomenon of electromagnetically induced transparency(EIT)that is originally observed in atomic gases offers diverse applications for new photonic components such as nonlinear optical units,slow-light devices,and biosensors.The development of functional integrated photonic devices requires an active control of EIT in metasurfaces.We demonstrate a reversible switching of the metasurface-induced transparency in the near-infrared region by incorporating a nonvolatile phase change material,Ge2Sb2Te5,into the metasurface design.This leads to an ultrafast reconfigurable transparency window under an excitation of a nanosecond pulsed laser.The measurement agrees well with both theoretical calculation and finite-difference time-domain numerical simulation.Our work paves the way for dynamic metasurface devices such as reconfigurable slow light and biosensing.展开更多
In theory, we study the quantum tluctuatlons ot tlae suDllarmonlc renecteu nela Irom a ulplc-rc^ulltUtt IdU^ClIClatC optical parametric amplifier (OPA) inside an optical cavity. We discuss two cases, where the linew...In theory, we study the quantum tluctuatlons ot tlae suDllarmonlc renecteu nela Irom a ulplc-rc^ulltUtt IdU^ClIClatC optical parametric amplifier (OPA) inside an optical cavity. We discuss two cases, where the linewidth of the harmonic field is either much narrower or broader than the subharmonic field. Since an electromagnetically-induced-transparency (EIT)-like effect can be simulated in a triple-resonant OPA, the output spectra from a triple-resonant OPA with a squeezed vacuum input may simulate the phenomenon of the response of an EIT medium for squeezed states. This scheme can be implemented with present experimental setups.展开更多
基金Project(61275174)supported by the National Natural Science Foundations of ChinaProject(20100162110068)supported by the Doctoral Program of Higher Education of China
文摘Based on Fabry model and finite-different time-domain(FDTD) method, the plasmonic structure composed of a metal-insulator-metal(MIM) bus waveguide and a side-coupled resonator was investigated. It is found that the transmission features can be regulated by the cavity width and coupling distance. Electromagnetically induced transparency(EIT)-like transmission can be excited by adding an identical resonator on the pre-existing structure. Combining the foregoing theoretical analysis with coupled mode theory(CMT), the formation process of the EIT-like transmission was detailedly analyzed. EIT-like transmission can also be excited in plasmonic structure with two detuned resonators. By altering the structure parameters, the transparency window can be purposefully modulated. With the merits of compact structure and simplicity in fabrication, the proposed structures may have a broad prospect of applications in highly integrated optical circuits.
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.
文摘This paper proposes a new metamaterial design that can achieve electromagnetic induction transparency-like (EIT-like) effects in the microwave band. The unit structure of metamaterials consists of square rings and metal wires. The square ring acts as the “bright state” and the metal wire acts as the “dark state”. The destructive interference between the bright state and the dark state produces an EIT-like effect. In the simulation results, a transparent window centered at 4.00 GHz can be observed in the transmission spectrum. By studying the phase change of the transparent window, it is found that the group delay of the metamaterial structure can reach 0.39 ns at 4.00 GHz. This paper </span><span>also studies the influence of the refractive index of the medium on the</span><span> EIT-like effect. Numerical simulations show that such metamaterial is very sensitive to the refractive index of the medium, and the sensitivity is 15 mm/RIU. Our design can be extended to other frequency bands and may have potential applications in filtering, sensing, slow-light devices, and nonlinear optics.
基金Project supported by the National Basic Research Program of China(Grant No.2012CB921601)the National Natural Science Foundation of China(Grant Nos.11104172,11274213,61205215,and 61227902)+2 种基金the Project for Excellent Research Teams of the National Natural Science Foundation of China(Grant No.61121064)the Research Project for Returned Abroad Scholars from Universities of Shanxi Province,China(Grant No.2012-015)the Program for Science and Technology Star of Taiyuan,Shanxi,China(Grant No.12024707)
文摘We present an investigation of double-resonance optical pumping (DROP) spectra under the condition of single-photon frequency detuning based on a cesium 6S1/2-6P3/2-8S1/2 ladder-type system with a room-temperature vapor cell. Two DROP peaks are found, and their origins are explored. One peak has a narrow linewidth due to the atomic coherence for a counterpropagating configuration; the other peak has a broad linewidth, owing to the spontaneous decay for a coprop-agating configuration. This kind of off-resonant DROP spectrum can be used to control and offset-lock a laser frequency to a transition between excited states. We apply this technique to a multiphoton cesium magneto-optical trap, which can efficiently trap atoms on both red and blue sides of the two-photon resonance.
基金Supported by National Natural Science Foundation of China under Grant Nos 60378008 and 10574052.
文摘We show that it is possible to use a single sideband to induce two-photon transparency in a three-level cascade medium. The medium simultaneously absorbs two photons as a one-step process when the middle level is far off one-photon resonance. A resonant sideband coupling on the upper transition and the two-photon one-step process drive the medium into a trapped state, and the dominant component is the ground state. Thus almost all population is trapped in the ground state and the two-photon absorption is dramatically suppressed. We present a numerical calculation for arbitrary values of the atomic and field parameters and also provide an analytic description for the required conditions.
基金This work was supported by the National Natural Science Foundation of China(No.51877182).
文摘The harmonics and resonance of traction power supply systems(TPSSs)aggravate the electromagnetic interference(EMI)to adjacent metallic pipelines(MPs),which has aroused widespread concern.In this paper,an evaluation method on pipeline interference voltage under harmonic induction is presented.The results show that the Carson integral formula is more accurate in calculating the mutual impedance at higher frequencies.Then,an integrated train-network-pipeline model is established to estimate the influences of harmonic distortion and resonance on an MP.It is revealed that the higher the harmonic cur-rent distortion rate of the traction load,the larger the interference voltage on an MP.Particularly,the interference voltage is amplified up to 7 times when the TPSS resonates,which is worthy of attention.In addition,the parameters that affect the variation and sensitivity of the interference voltage are studied,namely,the pipeline coating material,locomotive position,and soil resistivity,indicating that soil resistivity and 3PE(3-layer polyethylene)anticorrosive coating are more sensitive to harmonic induction.Field test results show that the harmonic distortion can make the interference voltage more serious,and the protective measures are optimized.
基金supported by the International Science and Technology Cooperation Program of China(Grant No.2015DFG12630)support from LiaoNing Revitalization Talents Program(Grant No.XLYC1807237)
文摘Metasurface analogue of the phenomenon of electromagnetically induced transparency(EIT)that is originally observed in atomic gases offers diverse applications for new photonic components such as nonlinear optical units,slow-light devices,and biosensors.The development of functional integrated photonic devices requires an active control of EIT in metasurfaces.We demonstrate a reversible switching of the metasurface-induced transparency in the near-infrared region by incorporating a nonvolatile phase change material,Ge2Sb2Te5,into the metasurface design.This leads to an ultrafast reconfigurable transparency window under an excitation of a nanosecond pulsed laser.The measurement agrees well with both theoretical calculation and finite-difference time-domain numerical simulation.Our work paves the way for dynamic metasurface devices such as reconfigurable slow light and biosensing.
基金supported by the National Basic Research Program of China (Grant No. 2011CB921601)the National Natural Science Foundation of China for Excellent Research Team (Grant No. 61121064)+1 种基金the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20111401130001)the Graduate Outstanding Innovation Item of Shanxi Province, China (Grant No. 20113001)
文摘In theory, we study the quantum tluctuatlons ot tlae suDllarmonlc renecteu nela Irom a ulplc-rc^ulltUtt IdU^ClIClatC optical parametric amplifier (OPA) inside an optical cavity. We discuss two cases, where the linewidth of the harmonic field is either much narrower or broader than the subharmonic field. Since an electromagnetically-induced-transparency (EIT)-like effect can be simulated in a triple-resonant OPA, the output spectra from a triple-resonant OPA with a squeezed vacuum input may simulate the phenomenon of the response of an EIT medium for squeezed states. This scheme can be implemented with present experimental setups.