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- 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
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Semi-integer harmonic generation from an argon atom by bichromatic counter-rotating circularly polarized laser field
摘要： We theoretically investigated the properties of the high-order harmonic generation from an argon atom by bichromatic counter-rotating circularly polarized (BCCP) laser field. The harmonic spectra are gradually splitting and the harmonic orders move towards the higher frequency. Meanwhile, the integer and semi-integer harmonic emission will be generated when the frequency ratios of right- and left-circularly polarized laser are semi-integer. The emission mechanism of the semi-integer-order harmonics have been investigated by using the rules of photon absorption and emission.
关键词： bichromatic counter-rotating circularly polarized laser field,photon absorption and emission,high-order harmonic generation,semi-integer-order
更新于2025-09-23 15:21:01
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A right-handed circularly polarized wave generated by a waveguide-fed holographic metasurface
摘要： We propose a novel method superposed two linearly polarized components to generate a right-handed circularly polarized (RCP) wave by using a holographic waveguide-fed metasurface. Combining with the holography principle and the polarizable particles based method, the expected RCP wave can be steered flexibly only by changing the slot state of each unit cell. A prototype generating a RCP wave at boresight direction is simulated, fabricated and measured, respectively. Both simulation and experiment results verify the good capability of the proposed metasurface. Applying this method, the resultant metasurface does not need a complex feeding network and can be easily extended to a reconfigurable CP metasurface. Therefore, the proposal has a huge potential in reconfigurable multifunctional CP devices.
关键词： waveguide-fed,metasurface,circularly polarized wave,holography
更新于2025-09-23 15:21:01
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Circularly Polarized Rooma??Temperature Phosphorescence and Encapsulation Engineering for MOFa??Based Fluorescent/Phosphorescent WLEDs
摘要： Optical materials with circularly polarized luminescence and room temperature phosphorescence currently attract great attention owing to their unique optoelectronic properties. Herein, via the coordination-induced assembly strategy, a homochiral metal–organic framework (MOF) 1 with high stability and porosity is successfully synthesized by using the achiral triphenylamine-based molecule as the building block. Remarkably, MOF 1 shows circularly polarized luminescence and phosphorescence at room temperature simultaneously, also with excellent anisotropic optical properties. Furthermore, MOF 1 can serve as a nanocontainer to construct dye-encapsulated host–guest systems. Importantly, the multicolor emissions including white-light emission can be achieved. The corresponding color rendering index and correlated color temperature values of light emitting device are 73 and 5541 K, when using dye-loaded MOF 1?RhB 10 (CIE: 0.33, 0.33) as single-phase white light-emitting phosphor. This study first reports circularly polarized phosphorescence based on MOF without precious metals under ambient conditions, and also is first time for phosphorescent polarized materials with high porosity. These results will open up a new pathway to the design of porous chiroptical materials and white-light materials.
关键词： circularly polarized luminescence,host–guest system,room temperature phosphorescence,white light emitting devices,metal–organic frameworks
更新于2025-09-23 15:21:01
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The comparison of high-order harmonic generation of H$_{2}^{+ }$ in a circularly polarized laser pulse combined with a terahertz field and with a static electric field
摘要： By solving a two-dimensional time-dependent Schr?dinger equation we investigate high-order harmonic generation (HHG) for the H+2 molecular ion in a circularly polarized laser pulse (CPLP). A comparison is made between a HHG in a CPLP combined with a terahertz (THz) field and with a static electric field. When the CPLP is combined with a static electric field, it is observed that a double-plateau structure appears, and the harmonic spectrum presents large modulation. With the CPLP with a THz field, a continuum spectrum with a spectral width of about 137 eV from 102 eV to 239 eV can be achieved. The HHG process is studied using the semi-classical three-step model and time-frequency analysis. Our studies show that only one trajectory contributes to HHG when a THz field is added. Furthermore, we present the temporal evolution of the probability density of an electron wave packet, which shows the recombination of electrons at different times.
关键词： circularly polarized laser pulse,quantum path control,high-order harmonic generation
更新于2025-09-23 15:21:01
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Dynamics of strong-field double ionization of H <sub/>2</sub> in co-rotating two-color circularly polarized laser fields
摘要： Double ionization of H2 in a co-rotating two-color circularly polarized (TCCP) laser ?eld is theoretically investigated. By changing the ratio of electric ?eld peak amplitudes of the TCCP laser pulses, the double ionization probability as a function of the laser intensity shows a clear knee structure, which is suppressed signi?cantly in the case of the atom. Due to the large spatial range of the electronic initial distribution, with the analysis of classical trajectories of ionized electrons, it is found that the ionization of the electron in the farther distance increases the probability of recollision. Furthermore, the yield of nonsequential double ionization created by the recollision can be enhanced by controlling the amplitude ratio of the TCCP laser ?eld.
关键词： knee structure,circularly polarized laser ?eld,H2
更新于2025-09-23 15:21:01
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A metasurfacea??enabled wideband higha??gain duala??circularlya??polarized Fabrya??Perot resonator antenna
摘要： This paper presents a wideband high-gain dual-circularly-polarized (CP) antenna with a simple configuration. Instead of improving the gain using the dual-CP element array, the Fabry-Perot resonator antenna concept is applied in this work. By designing a dual-linearly-polarized Fabry-Perot resonator antenna and a linear-to-circular polarization (LP-CP) metasurface polarizer separately and combining them, a wideband high-gain dual-CP antenna can be achieved. Structural simplicity and less design difficulty are advantages of the antenna design. Experimental results validate the design concept. It exhibits 3-dB axial-ratio bandwidths of over 12% for both LHCP and RHCP performance, a high polarization isolation of over 25 dB, and peak gains of 12.78 dBi and 12.89 dBi for LHCP and RHCP radiations respectively.
关键词： wideband,metasurface,dual-circularly-polarized,high-gain,Fabry-Perot resonator antennas
更新于2025-09-23 15:21:01
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High Circular Polarized Nanolaser with Chiral Gammadion Metal Cavity
摘要： We demonstrate a circularly polarized laser with the metal-gallium-nitride gammadion nanocavities. The ultraviolet lasing signal was observed with the high circular dichroism at room temperature under pulsed optical pump conditions. Without external magnetism which breaks the time-reversal symmetry to favor optical transitions of a chosen handedness, the coherent outputs of these chiral nanolasers show a dissymmetry factor as high as 1.1. The small footprint of these lasers are advantageous for applications related to circularly polarized photons in future integrated systems, in contrast to the bulky setup of linearly-polarized lasers and quarter-wave plates.
关键词： ultraviolet lasing,gammadion nanocavities,circular dichroism,chiral nanolasers,circularly polarized laser
更新于2025-09-23 15:21:01
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Pathways to excitation of atoms with bicircular laser pulses
摘要： We study the excitation of the hydrogen atom by bichromatic circularly polarized laser pulses using numerical solutions of the time-dependent Schr?dinger equation. The results are in agreement with the selection rules for multiphoton processes in such fields, namely, excited states are populated in which orbital angular momentum and magnetic quantum numbers are either both odd or both even, independent of the relative helicity, peak intensity, and pulse duration of the pulses. For co-rotating pulses the results show that excitation predominantly proceeds to states with magnetic quantum number of the same helicity as the laser pulses. Besides pathways via direct photon absorption from the ground state our results indicate that a transfer of population among the Rydberg states occurs via (cid:2)-type transitions. In the case of counter-rotating pulses the largest excitation probability is found for Rydberg states that differ in magnetic quantum number by (cid:3)m = ±3. This pattern allows us to estimate how many photons from each of the two bichromatic fields have been absorbed. Finally, we confirm that a population in Rydberg states beyond a maximum orbital angular quantum number is unlikely.
关键词： Rydberg states,hydrogen atom,bichromatic circularly polarized laser pulses,time-dependent Schr?dinger equation,multiphoton processes
更新于2025-09-23 15:21:01
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Asymmetry flip in angle-resolved photoelectron spectra of rare gas atoms by intense circularly polarized few-cycle pulses
摘要： We examine the phenomenon of the flip in the asymmetry in the emission direction of photoelectrons from rare gas atoms upon the ionization by a circularly polarized few-cycle laser field, and derive an analytical formula representing the photoelectron kinetic energy at which the asymmetry flip occurs based on the semiclassical tunnel ionization theory. We show that the energy at which the asymmetry flip occurs varies sensitively to the duration of few-cycle laser pulses and propose that the pulse duration can be determined experimentally using this analytical formula for the asymmetry flip energy.
关键词： asymmetry flip,photoelectron spectra,rare gas atoms,circularly polarized few-cycle pulses
更新于2025-09-23 15:21:01
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Planar Chiral [2.2]Paracyclophanes: Optical Resolution and Transformation to Optically Active π-Stacked Molecules
摘要： In this article, recent our results on practical optical resolution methods of disubstituted and tetrasubstituted [2.2]paracyclophane compounds and their transformations are described. The obtained enantiopure [2.2]paracyclophane compounds have been used as chiral building blocks to prepare optically active π-stacked molecules. π-Stacked molecules construct optically active second-ordered structures, such as V-, N-, M-, X-, triangle-shaped, and one-handed double helical structures, due to the orientation of stacked π-electron systems. They emit circularly polarized luminescence (CPL) by photo-excitation. [2.2]Paracyclophane-based chiral π-stacked molecules in this article emit brightly owing to good photoluminescence (PL) quantum efficiencies as well as large molar extinction coefficients. In particular, emission is of course CPL with the large disymmetry factor (glum value). It is basically difficult to achieve CPL with high brightness, high PL efficiency, and large glum value by using other chiral scaffolds; therefore, planar chiral [2.2]paracyclophane is the ideal scaffold to be an excellent CPL emitters.
关键词： [2.2]Paracyclophane,Planar chirality,Circularly polarized luminescence
更新于2025-09-23 15:21:01