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Enhanced and tunable circular dichroism in the visible waveband by coupling of the waveguide mode and local surface plasmon resonances in double-layer asymmetric metal grating 下载免费PDF全文
Liu-Li Wang 《中国物理 B》2022,31(11):118103-118103
Circular dichroism (CD) has shown very interesting possibilities as a means to characterize the chiral signal of a chiral structure. Here, we theoretically demonstrated enhanced and tunable CD in the visible light regime using a composite structure consisting of a double-layer metal grating gaped by a dielectric waveguide layer. Based on the coupling of the waveguide modes and the localized plasmonic resonances, the CD could reach a maximum value as high as 0.52 at 635 nm, which is four times higher than the CD value obtained in a conventional double-layer grating without the waveguide coupling effect. Furthermore, the spectral positions of the enhanced CD bands could be easily tuned by controlling the structural parameters. The proposed hybrid double-grating and waveguide structures could have potential applications in chiral selective imaging, sensing and spectroscopy, especially where the transmission measurement is required. 相似文献
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The obvious circular dichroism(CD) and optical activity can be obtained based on the chiral metamaterial due to the plasmon-enhanced effect, which is very attractive for future compact devices with enhanced capabilities of light manipulation. In this paper, we propose a dual-chiral metamaterial composed of bilayer asymmetric split ring resonators(ASRR)that are in mirror-symmetry shape. It is demonstrated that the CD can get enhancement in the terahertz regime. Moreover,the CD can be further improved by modulating the asymmetry of ASRR. The enhanced CD effect in the terahertz regime has great potential applications in sensing, biomedical imaging, and molecular recognition. 相似文献
4.
C.R. Natoli C. Brouder P. Sainctavit J. Goulon C. Goulon-Ginet A. Rogalev 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,4(1):1-11
A method is presented to calculate the natural circular dichroism recently discovered in the X-ray range (XNCD). The basic
formula represents XNCD as an odd second-rank tensor and leads to a sum rule that relates XNCD to the mixing of odd and even
orbitals in the ground state. A multiple-scattering theory of XNCD is presented, and calculated spectra for the L-edges of
iodine in LiIO3 compare favorably with the experiments.
Received: 20 October 1997 / Revised: 18 February 1998 / Accepted: 31 March 1998 相似文献
5.
Efficiency of the structure analysis of complex molecules in the gas phase by their optical rotation
V. A. Tolkachev 《Journal of Applied Spectroscopy》1998,65(6):883-890
It was shown in the dipole approximation of optical rotation that in the general case only in orientationally anisotropic
vapors is the rotational force dependent on the intramolecular orientation of both the electric and magnetic dipole moments.
Expressions relating the optical rotational force to the intramolecular orientation of these moments, the orientational distribution
in an anisotropic ensemble, and the configuration of a measurement have been obtained. Calculated dependences of the rotational
force on the intramolecular orientation of the magnetic moment at a fixed electric moment and “rotational force excitation
spectra” obtained for different types of rigid asymmetric top molecules and rotational contours are presented. It is proposed
to measure the intramolecular orientation of the electric and magnetic dipole moments with the use of the rotational force
normalized to that detected in the case of observation at a “magic” angle to the direction of the exciting light electric
vector.
Institute of Molecular and Atomic Physics of the Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 6, pp. 843–849, November–December, 1998. 相似文献
6.
Summary An extension of a recent model explaining the stability of chiral molecules is presented here. From the comparison between
the energy reduction produced by the adoption of a chiral form and that produced by a symmetric superposition of chiral states
it is concluded that the true fundamental state of the chiral molecules is the chiral one, which eliminates the well-known
?optical-isomers paradox?. Also, a discussion on the main differences between the approach used here and the previous attempts
of explanation based in the double-well model is made.
The authors of this paper have agreed to not receive the proofs for correction. 相似文献
7.
Helical twisting power and circular dichroism in nematic liquid crystals doped with chiral molecules
Explicit expressions for the helical twisting power of a chiral dopant in the nematic phase have been obtained in the mean field approximation taking into account chiral dispersion intermolecular interactions. The results of the theory enable one to explain a correlation between the signs of helical twisting power and circular dichroism of selected electronic transitions which have recently been established experimentally for some mono- and bis-aminoantroquinones. Helical twisting power is proportional to the pseudoscalar parameter that specifies the chirality of the dopant molecule in terms of its dipole and quadrupole matrix elements. This expression is simplified for a special class of molecules in which chirality is induced by a perturbing achiral group into an achiral skeleton. In this case both helical twisting power and circular dichroism are approximately proportional to some simple pseudoscalar functions that specify the location of the achiral perturbing group with respect to the symmetry planes of the unperturbed achiral skeleton. Simple sector rules have been proposed to determine the sign change of the helical twisting power associated with the change of location of the perturbing group. 相似文献
8.
Helical twisting power and circular dichroism in nematic liquid crystals doped with chiral molecules
The European Physical Journal E - Explicit expressions for the helical twisting power of a chiral dopant in the nematic phase have been obtained in the mean field approximation taking into account... 相似文献
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A. A. Kokhanovskii 《Journal of Applied Spectroscopy》1991,55(4):1041-1046
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 55, No. 4, pp. 645–650, October, 1991. 相似文献
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基于手性结构设计了一种极化不敏感和双面吸波的超材料吸波体.该吸波体的结构单元由手性结构和介质基板组成.仿真的电磁波正、反向入射时超材料吸波体的吸收率表明:该吸波结构的正、反面是互易的,具有双面吸波特性.仿真的不同极化角下超材料吸波体的吸收率表明:该超材料吸波体具有极化不敏感特性.仿真的不同入射角下超材料吸波体的吸收率表明:该超材料吸波体的入射角较窄.仿真的吸波体单元的表面电流和磁能密度分布表明:电、磁场之间存在交叉耦合,吸波与手性有关.仿真的不同损耗情况下超材料吸波体的吸收率表明:基板的介质损耗在吸波过程中起主导作用,金属的电阻热可以忽略不计.该超材料吸波体可能在要求双面吸波的领域中具有潜在的应用.
关键词:
极化不敏感
双面吸波
手性结构
超材料吸波体 相似文献
12.
Silver chiral nano-flowers with 3-, 4- and 5-fold symmetry were produced using oblique angle deposition method in conjunction with the rotation of sample holder with different speeds at different sectors of each revolution corresponding to symmetry order of the acquired nano-flower. Atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM), were employed to obtain morphology and nano-structure of the films. Optical characteristics of silver chiral nano-flower thin films were obtained using single beam spectrophotometer with both s- and p-polarization incident light at 30° and 70° incidence angles and at different azimuthal angles (φ). Optical spectra showed both TM (TDM (transverse dipole mode) and TQM (transverse quadruple mode)) and LM (longitudinal mode) Plasmon resonance peaks. For 3- and 4-fold symmetry chiral nano-flowers the s-polarization extinction spectra obtained at different azimuthal angles did not show significant change in the Plasmon peak position while 5-fold symmetry chiral nano-flower showed a completely different behavior, which may be the result of increased surface anisotropy, so when the φ angle is changed the s-polarization response from the surface can change more significantly than that for lower symmetries. In general, for 3-, 4- and 5-fold symmetry chiral nano-flowers a sharp peak at lower wavelengths (<450 nm) is observed in the s-polarization spectra, while in addition to this peak a broad peak at longer wavelengths (i.e., LM) observed in the p-polarization spectra, which is more dominant for 70° incidence angle. 相似文献
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《Comptes Rendus Physique》2002,3(4):429-437
Nonlinear optical activity in chiral molecules is investigated. We first examine the importance of the nonlocality of the light–matter interaction in optical activity and extend this concept to second-order (surface second harmonic generation) and third-order (nonlinear circular dichroism) nonlinear optical phenomena. Microscopic models are also discussed. Various phenomena derived from these considerations are demonstrated experimentally with specially-synthesized chiral molecules. To cite this article: F. Hache et al., C. R. Physique 3 (2002) 429–437. 相似文献
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《Current Applied Physics》2018,18(11):1182-1184
The combination of angular spin momentum with electronics is a promising successor to charge-based electronics. The conduction bands in GaAs may become spin-polarized via optical spin pumping, doping with magnetic ions, or induction of a moment with an external magnetic field. We investigated the spin populations in GaAs with x-ray magnetic circular dichroism for each of these three cases. We find strong anti-symmetric lineshapes at the Ga L3 edge indicating conduction band spin splitting, with differences in line width and amplitude depending on the source of spin polarization. 相似文献
15.
This paper explores the feasible use of circular optical grating for measuring the rotation of mirrors that are commonly found in micro-systems. Both theoretical and experimental results show that distortion of the circular grating that is projected onto the mirror surface is a simple function of the angular rotation of the mirror. The circular grating may readily be generated using a standard Michelson interferometer or an LCD projector. Through manipulating the distance between the interferometer and the mirror surface, the diameter of the optical grating may be varied. Furthermore, the additional use of a converging lens enables a significant reduction in the size of the grating: with simple laboratory facility, small circular grating of about 400 μm is achieved for use on micro-systems. With the use of more sophisticated optical elements, the angular rotation of even smaller micro-mirrors may be measured. 相似文献
16.
Key rotation multiplexing for multiple-image optical encryption in the Fresnel domain 总被引:1,自引:0,他引:1
Xiao Yong-Liang Xianyu Su Sikun Li Xiaoqing Liu Shuguang Zeng 《Optics & Laser Technology》2011,43(4):889-894
We introduce a key rotation multiplexing method into the double random phase encoding system for multiple-image optical encryption in the Fresnel domain. Each plaintext is encoded into a stationary-white-noise ciphertext by the same only phase mask located at the input plane, and another only phase mask with a certain rotation angle located at the transform plane. All ciphertexts encoded from different plaintexts are added together to produce a final ciphertext, which serves as a single data source for different plaintexts decryption. Thus, the mask located at transform plane can be utilized to decrypt different plaintexts with a certain rotation angle. Also, we perform computer simulations to investigate how the quantization level of decrypted key and CCD, respectively, affect the decrypted quality and the number of images that can be multiplexed. 相似文献
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We present a bi-layer Y-shaped chiral metamaterial (CMM) that can realize a giant optical activity and circular dichroism (CD) effect to the incident linear polarization wave in the terahertz (THz) region. Numerical simulation results exhibit that the pronounced CD effect with a great difference between the transmission coefficients for the circularly polarized waves can be obtained at 5.06 THz, meanwhile the 90°-polarization rotation can be observed at 5.2 THz when a y-polarized wave is incident to this CMM propagating along the −z-axis. The mechanism of the optical activity and giant CD effect is illustrated by simulated surface current distributions. Further, the influences of the structural parameters of the proposed CMM to the optical activity and CD effect have been investigated numerically. 相似文献
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Ben Hopkins Alexander N. Poddubny Andrey E. Miroshnichenko Yuri S. Kivshar 《Laser \u0026amp; Photonics Reviews》2016,10(1):137-146
We present a general theory of circular dichroism in planar chiral nanostructures with rotational symmetry. It is demonstrated, analytically, that the handedness of the incident field's polarization can control whether a nanostructure induces either absorption or scattering losses, even when the total optical loss (extinction) is polarization‐independent. We show that this effect is a consequence of modal interference so that strong circular dichroism in absorption and scattering can be engineered by combining Fano resonances with planar chiral nanoparticle clusters.
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A planar chiral nanostructure with asymmetric transmission of linearly polarized wave and huge optical activity in near-infrared band 下载免费PDF全文
Just like an electronic diode that allows the electrical current to flow in one direction only, a kind of chiral metamaterial structure with a similar functionality for the electromagnetic wave is proposed. The designed nanostructure that consists of twisted metallic split-ring resonators on both sides of a dielectric substrate achieves asymmetric transmission for a forward and backward propagating linearly polarized wave by numerical simulation in near-infrared band. Difference in transmission efficiency of the optimized structure between the same polarized waves incident from opposite directions can reach a maximum at the communication wavelength (1.55 μm). Moreover, the simulation results of this structure also exhibit strong optical activity and circular dichroism. 相似文献
20.
The design characteristics of the optical cuvette suggested here provide the possibility of accomplishing the uniaxial orientation
of gels with retention of the constancy of their volume, which makes it possible to carry out highly accurate polarization
measurements with commercial spectropolarimeters in directions parallel and perpendicular to the axis of orientation. Using
as examples polyacrylamide gels containing biologically important molecules and membranes, the possibility of measuring absorption
spectra, the linear dichroism, and the dispersion of optical rotation is demonstrated.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 2, pp. 286–289, March–April, 1999. 相似文献