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Dr. Jiang Peng Jiakun Bai Xiumian Cao Jieting He Prof. Weiqing Xu Dr. Junhui Jia 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(64):16036-16042
Elastic organic single crystals with light-emitting and multi-faceted bending properties are extremely rare. They have potential application in optical materials and have attracted the extensive attention of researchers. In this paper, we reported a structurally simple barbituric derivative DBDT , which was easily crystallized and gained long needle-like crystals (centimeter-scale) in DCM/CH3OH (v/v=2/8). Upon applying or removing the mechanical force, both the (100) and (040) faces of the needle-like crystal showed reversible bending behaviour, showing the nature of multi-faceted bending. The average hardness (H) and elastic modulus (E) were 0.28±0.01 GPa and 4.56±0.03 GPa for the (040) plane, respectively. Through the analysis of the single crystal data, it could be seen that the van der waals (C−H⋅⋅⋅π and C−H⋅⋅⋅C), H-bond (C−H⋅⋅⋅O) and π⋅⋅⋅π interactions between molecules were responsible for the generation of the crystal elasticity. Interestingly, elastic crystals exhibited optical waveguide characteristics in straight or bent state. The optical loss coefficients measured at 627 nm were 0.7 dBmm−1 (straight state) and 0.9 dBmm−1 (bent state), while the optical loss coefficient (α) were 1.5 dBmm−1 (straight state) and 1.8 dBmm−1 (bent state) at 567 nm. Notably, the elastic organic molecular crystal based on barbituric derivative could be used as the candidate for flexible optical devices. 相似文献
74.
We study optical analogues of higher-order Dirac solitons (HODSs) in binary waveguide arrays. Like higher-order solitons obtained from the well-known nonlinear Schrödinger equation governing the pulse propagation in an optical fiber, these HODSs have amplitude profiles which are numerically shown to be periodic over large propagation distances. At the same time, HODSs possess some unique features. Firstly, the period of a HODS depends on its order parameter. Secondly, the discrete nature in binary waveguide arrays imposes the upper limit on the order parameter of HODSs. Thirdly, the order parameter of HODSs can vary continuously in a certain range. 相似文献
75.
Glenn Mangelinckx Jeroen Beeckman Olga Chojnowska Jungsoon Shin James D.K. Kim Roman Dąbrowski 《Liquid crystals》2013,40(11):1553-1558
This paper describes a novel implementation of a dual-frequency liquid crystal optical shutter of the guest–host type. The transmissive state of the filter is obtained by applying a low-frequency electric field that brings the dichroic dye in a homeotropic orientation. The light-absorbing state is realised by a twisted planar configuration for which the absorption is quasi-independent of the polarisation. Switching between the two states occurs in about 1 ms and the devices show no scattering for wavelengths inside or outside the absorption band of the dichroic dye. Simulations and experiments reveal how a twisted state is obtained through the backflow phenomenon. 相似文献
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77.
Qingqing Cheng Yiming Pan Qianjin Wang Tao Li Shining Zhu 《Laser \u0026amp; Photonics Reviews》2015,9(4):392-398
Recent realization of nontrivial topological phases in photonic systems has provided unprecedented opportunities in steering light flow in novel manners. Based on the Su–Schriffer–Heeger (SSH) model, a topologically protected optical mode was successfully demonstrated in a plasmonic waveguide array with a kinked interface that exhibits a robust nonspreading feature. However, under the same excitation conditions, another antikinked structure seemingly cannot support such a topological interface mode, which appears to be inconsistent with the SSH model. Theoretical calculations are carried out based on the coupled‐mode theory, in which the mode properties, excitation conditions, and the robustness are studied in detail. It is revealed that under the exact eigenstate excitations, both kinked and antikinked structures do support such robust topological interface modes; however, for a realistic single‐waveguide input only the kinked structure does so. It is concluded that the symmetry of interface eigenmodes plays a crucial role, and the odd eigenmode in a kinked structure offers the capacity to excite the nonspreading interface mode in the realistic excitation of a one‐waveguide input. Our finding deepens the understanding of mode excitation and propagation in coupled waveguide systems, and could open a new avenue in optical simulations and photonic designs.
78.
Daoxin Dai Jian Wang Sitao Chen Shipeng Wang Sailing He 《Laser \u0026amp; Photonics Reviews》2015,9(3):339-344
A compact 64‐channel hybrid demultiplexer based on silicon‐on‐insulator nanowires is proposed and demonstrated experimentally to enable wavelength‐division‐multiplexing and mode‐division‐multiplexing simultaneously in order to realize an ultra‐large capacity on‐chip optical‐interconnect link. The present hybrid demultiplexer consists of a 4‐channel mode multiplexer constructed with cascaded asymmetrical directional‐couplers and two bi‐directional 17 × 17 arrayed‐waveguide gratings (AWGs) with 16 channels. Here each bi‐directional AWG is equivalent as two identical 1 × 16 AWGs. The measured excess loss and the crosstalk for the monolithically integrated 64‐channel hybrid demultiplexer are about ‐5 dB and ‐14 dB, respectively. Better performance can be achieved by minimizing the imperfections (particularly in AWGs) during the fabrication processes.
79.
Iron is one of the most microbiologically and chemically important metals in natural waters. The biogeochemical cycling of iron is significantly influenced by the redox cycling of Fe(II) and Fe(III). Because of the unique chemistry of iron, it is often needed to analyze iron at nano-molar concentrations. This article describes a reverse flow injection analysis (rFIA) based method with ferrozine spectrophotometric detection to quantify total iron concentration in stream water at nanomolar concentrations. The rFIA system has a 0.65 nM detection limit and a linear dynamic range up to 1.40 μM for the total iron analysis. The detection limit was achieved using a 1.0 m long liquid waveguide capillary flow cell, 1.50 m long knotted reaction coil, 87.50 μL injection loop and a miniature fiber optics spectrophotometer. The optimized colorimetric reagent has 1.0 mM ferrozine, 0.1 M ascorbic acid, 1.0 mM citric acid and 0.10 M acetate buffer adjusted to pH 4.0. The best sample flow rate is 2.1 mL min?1 providing a sample throughput of more than 15 samples h?1. The linear dynamic range of the method can be adjusted by changing the volume of the injection loop. The rFIA manifold was assembled exclusively from commercially available components. 相似文献
80.
Inspired by the problem of elastic wave scattering on wrinkled interfaces, we studied the scattering of ballistic electrons on a wrinkled potential energy region. The electron transmission coefficient depends on both wrinkle amplitude and periodicity, having different behaviors for positive and negative scattering potential energies. For scattering on potential barriers, minibands appear in the electron transmission, as in superlattices, whereas for scattering on periodic potential wells the transmission coefficient has a more complex form. Besides suggesting that tuning of electron transmission is possible by modifying the scattering potential via voltages on wrinkled gate electrodes, our results emphasize the analogies between ballistic electrons and elastic waves even in scattering problems on non-typical configurations. 相似文献