- 标题
- 摘要
- 关键词
- 实验方案
- 产品
过滤筛选
- 2018
- circularly polarized (CP) antenna
- Elliptical microstrip antenna (EPMA)
- impedance bandwidth (IBW)
- defected ground (DG) technique
- multi-layered stacked structure
- axial ratio bandwidth (ARBW)
- Optoelectronic Information Science and Engineering
- Bhagwant University, Ajmer, Rajasthan, India
- Govt Mahila Engineering College, Ajmer, Rajasthan, India
-
irradiated by a co-rotating two-color circularly polarized laser field
摘要： The high-order harmonic generation process of H2+ in a co-rotating two-color circularly polarized laser pulse was investigated by numerically solving the time-dependent Schr?dinger equation. Compared with the target of the atom, the harmonic intensity of H2+ is remarkably enhanced. Moreover, the harmonic intensity of H2+ approaches its maximum when the electric field amplitude ratio of the fundamental frequency and the second one is approximately 1:2.3. By analyzing the evolution of the time-dependent wave packets, the enhancement of harmonic intensity may be attributed to an increase in the probability of the ionized electron recolliding with the parent ion. In addition, the dependence of harmonic intensity on the internuclear distance and the alignment angle of H2+ is explored. We found that the ellipticity of the particular harmonic order changes with the molecular alignment angle, which provides a chance to generate an extreme ultraviolet coherent light pulse with controllable polarization.
关键词： time-dependent Schr?dinger equation,H2+,harmonic intensity,alignment angle,extreme ultraviolet coherent light pulse,controllable polarization,co-rotating two-color circularly polarized laser field,internuclear distance,high-order harmonic generation
更新于2025-09-12 10:27:22
-
Finely Controlled Circularly Polarized Luminescence of a Mechano-Responsive Supramolecular Polymer
摘要： We report on finely controlled circularly polarized luminescence (CPL) supramolecular polymerization based on a tetraphenylethene core with four L- or D-alanine branch side chains (L-1 and D-1) in the solution state resulting from the tuning of mechanical stimulus. Weak, green emissions of L-1 and D-1 in tetrahydrofuran (THF) were converted to strong blue emissions by tuning the mechanical stimulus. The strong blue emissions were caused by an aggregation-induced emission (AIE) effect during the formation of a supramolecular polymer. Lag time in the supramolecular polymerization was drastically reduced by the mechanical stimulus, which was indicative of the acceleration of the supramolecular polymerization. Interestingly, a significant enhancement of circular dichroism (CD) and CPL signals of the L-1 and D-1 was observed by tuning the rotational speed of the mechanical stimulus, which implies that the chiral supramolecular polymerization was accelerated by the mechanical stimulus. These results imply that the CPL signals were tuned by the strength of the external mechanical stimulus.
关键词： Helicity,AIE Effect,Mechano-Responsive Material,Circularly Polarized Luminescence,Supramolecular Polymerization
更新于2025-09-11 14:15:04
-
[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Controlling Light Polarization from Helical Travelling-Wave Nanoantennas
摘要： Light polarization is a key factor of modern photonics. Tailoring surface plasmons (SPs) in anisotropically-shaped metallic nanostructures introduces the prospect of polarization control at small scale [1]. However, the resulting components remain much larger than the wavelength of light. Here, we present a travelling-wave helical plasmonic antenna (TW-HPA) that overcomes this limit [2]. Due to its non-resonant nature, it differs from existing helical plasmonic structures [3-5], thus extending the concept of travelling-wave helical antenna [6] to optics. Our TW-HPA consists of a narrow gold-coated wire wound up in a screw-like shape forming a tiny helix (Fig. 1a). The gold-coated wire sustains a cutoff-free axially symmetric travelling SPs [7], locally excited with the dipolar mode of a rectangular aperture nanoantenna right at the helix's pedestal. In the course of propagation, the plasmon wire mode acquires orbital angular momentum (OAM). Due to the sharp curvatures, the OAM of the SP mode match the spin angular momentum (SAM) of free-space propagating photons [8]. On the basis of this OAM-to-SAM transfer, individual TW-HPA can produce circularly polarized directional light on the subwavelength scale through a swirling-plasmon effect. Such TW-HPAs can then be closely packed to build micron scale arrangements of tiny circularly polarized light sources of desired handedness and tunable intensities, which could open new perspectives in a large panel of photonic applications requiring local addressing, such as detectors, displays, optomagnetic recording as well as quantum information. By optically coupling four TW-HPAs of opposite handedness (Fig.1b), we obtained a phase plate occupying a volume smaller than a cubic wavelength whose polarization properties have never previously been demonstrated. Switching between left and right circular polarizations (LCP and RCP) occurs when the incident linear polarization is rotated by an angle of 52°, instead of 90° as for standard quarter wave plates. Based on the spin-orbit interaction of light, our method is versatile, robust and leads to ultracompact plasmonic polarizers and unconventional phase plates. Taken as individual or coupled structures, TW-PHAs may pave the way towards highly integrated polarization-encoded optics, particularly for the generation and control of spin-encoded photon qubits in quantum information and optical spintronics.
关键词： Light polarization,orbital angular momentum,surface plasmons,circularly polarized light,optical spintronics,quantum information,spin angular momentum,helical travelling-wave nanoantennas
更新于2025-09-11 14:15:04
-
Helicity of harmonic generation and attosecond polarization with bichromatic circularly polarized laser fields
摘要： We theoretically investigate the high-order harmonic generation (HHG) of helium atom driven by bichromatic counter-rotating circularly polarized laser fields. By changing the intensity ratio of the two driving laser fields, the spectral chirality of the HHG can be controlled. As the intensity ratio increases, the spectral chirality will change from positive- to negative-value around a large intensity ratio of the two driving fields when the total laser intensity keeps unchanged. However, the sign of the spectral chirality can be changed from positive to negative around a small intensity ratio of the two driving fields when the total laser intensity changes. At this time, we can effectively control the helicity of the harmonic spectrum and the polarization of the resulting attosecond pulses by adjusting the intensity ratio of the two driving laser fields. As the intensity ratio and the total intensity of the driving laser fields increase, the relative intensity of either the left-circularly or right-circularly polarized harmonic can be enhanced. The attosecond pulses can evolve from being elliptical to near linear correspondingly.
关键词： spectral chirality,attosecond polarization,high-order harmonic generation,bichromatic circularly polarized laser fields
更新于2025-09-11 14:15:04
-
[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Comparative Study of Harmonic Generation in Air and Argon in Light Filaments Driven by Circularly Polarized Mid-IR Pulses
摘要： A generation of optical harmonics by circularly polarized light, which is in general forbidden in an isotropic medium, was recently observed in molecular gases where molecules were aligned and oriented by another linearly polarized laser pulse or by pulses with twisted polarization. In order to generate nth-harmonic with circularly polarized light, a molecule has to “absorb” n photons, having the same handedness, and to emit a single nth harmonic photon while fulfilling the energy and the momentum conservation laws, meaning a necessity to excite the molecule to appropriate rotational state. One can do this by means of intrapulse rotational Raman scattering, which prepares the molecule in the excited state through a subsequent absorption of (n-1) same-handed photons. All previously reported experimental studies on circular harmonic generation in molecular gases were performed with visible/near-IR drivers, in either gas jets or in standing cells and with pre-alignment of molecules by an additional laser pulses. Here we report on the studies of self-action of elliptically polarized mid-IR pulses on the generation of low-order harmonics in filaments ignited in air and in argon, representing a molecular and an atomic gas respectively. The harmonics were driven by 20-mJ, sub-100 fs mid-IR pulses, centred at 3.9 μm wavelength. In the experiments filamentation was assisted by focusing light with a spherical mirror of ROC=-2500 mm into an open-end tube, through which Ar gas was flown at slight overpressure. Polarization of the pulses was controlled by a broadband quarter wave plate (QWP). Spectra of 5th and 7th harmonics were recorded after the filaments with a grating spectrometer (HR4000, OceanOptics). Polarization state of the generated harmonics was analysed with a Glan-Taylor polarizer.
关键词： filaments,argon,circularly polarized light,mid-IR pulses,harmonic generation,air
更新于2025-09-11 14:15:04
-
Optically Controlled Orbitronics on a Triangular Lattice
摘要： The propagation of electrons in an orbital multiplet dispersing on a lattice can support anomalous transport phenomena deriving from an orbitally induced Berry curvature. In striking contrast to the related situation in graphene, we find that anomalous transport for an L ? 1 multiplet on the primitive 2D triangular lattice is activated by easily implemented on site and optically tunable potentials. We demonstrate this for dynamics in a Bloch band where point degeneracies carrying opposite winding numbers are generically offset in energy, allowing both an anomalous charge Hall conductance with the sign selected by off-resonance coupling to circularly polarized light and a related anomalous orbital Hall conductance activated by layer buckling.
关键词： Berry curvature,anomalous transport,circularly polarized light,triangular lattice,orbital Hall conductance
更新于2025-09-11 14:15:04
-
Triplet exciton fine structure in Pt-rich polymers studied by circularly polarized emission under high magnetic field
摘要： Incorporating heavy atoms into polymer chains represents an effective way to generate emissive triplets. Here we used magneto-optical emission spectroscopy up to 17.5 Tesla for studying the fine structure of the triplet exciton in a series of Pt-rich π-conjugated polymers with various intrachain Pt concentrations. We found that their phosphorescence emission band shows substantial field-induced circular polarization (FICPO) up to 50% with an unusual, nonmonotonic field dependence at cryogenic temperature. From the field-induced energy splitting between left and right circularly polarized phosphorescence we obtained the effective g factor of triplet exciton varying in the range of ?0.13-0.85, which depends on the Pt concentration in the polymer chains. The FICPO of triplet emission originates from the population difference in spin sublevels, which is determined by thermal equilibrium subjected to spin-orbit coupling (SOC), exchange, and Zeeman interactions. Surprisingly we also observed FICPO in the fluorescence emission that results from the singlet-triplet interaction caused by the strong SOC. From these results we extracted the various interaction parameters that describe the exciton fine structure in these Pt-contained compounds.
关键词： Pt-rich polymers,high magnetic field,circularly polarized emission,spin-orbit coupling,triplet exciton
更新于2025-09-11 14:15:04
-
-matrix-with-time-dependence theory for ultrafast atomic processes in arbitrary light fields
摘要： We describe an ab initio and nonperturbative R-matrix with time-dependence theory for ultrafast atomic processes in light fields of arbitrary polarization. The theory is applicable to complex, multielectron atoms and atomic ions subject to ultrashort (particularly few-femtosecond and attosecond) laser pulses with any given ellipticity, and it generalizes previous time-dependent R-matrix techniques restricted to linearly polarized fields. We discuss both the fundamental equations, required to propagate the multielectron wave function in time, as well as the computational developments necessary for their efficient numerical solution. To verify the accuracy of our approach, we investigate the two-photon ionization of He, irradiated by a pair of time-delayed, circularly polarized, femtosecond laser pulses, and compare photoelectron momentum distributions, in the polarization plane, with those obtained from recent time-dependent close-coupling calculations. The predictive capabilities of our approach are further demonstrated through a study of single-photon detachment from F? in a circularly polarized, femtosecond laser pulse, where the relative contribution of the co- and counter-rotating 2p electrons is quantified.
关键词： ultrafast atomic processes,R-matrix,circularly polarized laser pulses,single-photon detachment,time-dependence,photoelectron momentum distributions,arbitrary light fields,multielectron atoms
更新于2025-09-11 14:15:04
-
[IEEE 2018 Cross Strait Quad-Regional Radio Science and Wireless Technology Conference (CSQRWC) - Xuzhou, China (2018.7.21-2018.7.24)] 2018 Cross Strait Quad-Regional Radio Science and Wireless Technology Conference (CSQRWC) - Capacitive Probe Fed Broadband Circularly Polarized Omnidirectional Antenna
摘要： A (CP) omnidirectional antenna fed by a capacitive probe is presented in this paper. To attain wideband vertical polarization, a circular monopole patch connecting to the ground by a set of shorting pins is applied. Two groups of curved branches are introduced to create wideband horizontal polarization. The CP radiation can be generated with a proper phase difference between the vertical polarization and the horizontal polarization. The antenna is fabricated and measured. It exhibits an impedance bandwidth (VSWR≤2) of 34.6% (ranges from 4.50 to 6.38 GHz) and an axial ratio bandwidth (AR≤3dB) of 33.5% (ranges from 4.60 to 6.45 GHz). The profile of the antenna is merely 0.06λL (λL is the wavelength corresponding to the lowest operating frequency).
关键词： low profile,circularly polarized,coupling feed structure,omnidirectional antenna,broadband
更新于2025-09-10 09:29:36
-
Cooperative Chirality and Sequential Energy Transfer in Supramolecular Light-harvesting Nanotube
摘要： By constructing a supramolecular light-harvesting chiral nanotube in aqueous phase, we demonstrated the cooperative energy and chirality transfer that revealed some new aspects. It was found that a cyanostilbene-appended glutamate compound (CG) self-assembled into helical nanotubes exhibiting both supramolecular chirality and circularly polarized luminescence (CPL). When two achiral acceptors ThT and AO with different energy bands were co-assembled with the nanotube, the CG nanotube could transfer its chirality to both of the acceptors. The excitation energy could be transferred to ThT but only be sequentially transferred to AO. During such process, the CPL ascribed to the acceptor could be sequentially amplified. This work provides a new insight into the understanding the cooperative chirality and energy transfer in a chiral supramolecular system, which is more similar to the natural light-harvesting antennas.
关键词： Supramolecular chirality,Energy transfer,Light-harvesting,Circularly polarized luminescence,Supramolecular nanotube
更新于2025-09-10 09:29:36