A near-infrared light-driven self-organized emissive helical superstructure was constructed by doping a new chiral fluorescent photoswitch and upconversion nanoparticles (UCNPs) into a nematic LC. ...The reversible switching of circularly polarized luminescence (CPL) can be achieved by modulating the power intensity of the 980 nm NIR excitation light.
The reversible switching of circularly polarized luminescence in a self-organized emissive helical superstructure using 980 nm NIR excitation light with different power intensities is reported for the first time.
Metal-mediated assembly allows us to combine an achiral emissive ligand A with different chiral ligands (such as B) in a non-statistical fashion, obtaining Pd2A2B2 heteroleptic cages showing ...circularly polarized luminescence (CPL). By using the ‘shape complementary assembly’ (SCA) strategy, the cages are exclusively obtained as cis-Pd2A2B2 stereoisomers, as confirmed by NMR, MS and DFT analyses. Their unique chiroptical properties derive from the synergy of all the building blocks. Ligand B imparts the chiral information of its aliphatic backbone, comprising two stereogenic sp3 carbon centres, to the overall structure, causing CD and CPL signal induction for the chromophore on ligand A. The heteroleptic cage shows CPL with a |glum| value of 2.5 × 10−3, which is 3-times higher than that for a progenitor based on aromatic helical building block H, thus opening a rational route towards optimizing the CPL properties of self-assembled nanostructures in a modular way.
Multicomponent metallo‐supramolecular assembly allows the rational combination of different building blocks. Discrete multifunctional hosts with an accessible cavity can be prepared in a ...non‐statistical fashion. We employ our shape‐complementary assembly (SCA) method to achieve for the first time integrative self‐sorting of heteroleptic PdII cages showing guest‐tunable circularly polarized luminescence (CPL). An enantiopure helicene‐based ligand (M or P configuration) is coupled with a non‐chiral emissive fluorenone‐based ligand (A or B) to form a series of Pd2L2L′2 assemblies. The modular strategy allows to impart the chiral information of the helicenes to the overall supramolecular system, resulting in CPL from the non‐chiral component. Guest binding results in a 4‐fold increase of CPL intensity. The principle offers potential to generate libraries of multifunctional materials with applications in molecular recognition, enantioselective photo‐redox catalysis and information processing.
Integrative self‐assembly of PdII cations with an enantiopure helicene‐based ligand and non‐chiral but emissive fluorenone ligands yields a series of Pd2L2L′2 heteroleptic coordination cages, showing circularly polarized luminescence (CPL) from the non‐chiral moiety. Modulation of the chiroptical properties is achieved by ligand modification or guest binding, achieving an up to 4‐fold enhancement of CPL intensity.
While halide perovskites (HPs) have achieved enormous success in the field of optoelectronic applications, much attention has been recently drawn to the unique polarization sensitivity of HPs, either ...intrinsic or extrinsic, which makes HPs a potential candidate for innovative applications in directly polarized luminescence and detection. Herein, the research status in the field of polarization‐sensitive HPs, including linear polarization and circular polarization, is comprehensively summarized. To evaluate the effectiveness of HPs in generating and detecting linearly or circularly polarized light, the principles and characterization methods of polarized luminescence and detection are introduced. Sequentially, the state‐of‐the‐art development of the strategies that induce the linear or circular polarization characteristics of HPs is systematically reviewed, based on which the application of polarization‐sensitive HPs in the field of polarization luminescence and detection are summarized. Moreover, the current challenges and opportunities are discussed, and prospects of the future development in this promising field are outlined.
The current developments and advanced understanding of polarization‐sensitive halide perovskites are comprehensively reviewed, involving linear/circular polarization luminescence and detection. Also, the key challenges and current opportunities in the field are discussed. The great promise of polarization‐sensitive halide perovskites is addressed to inspire other potential applications in opotoelectronics.
The molecular machinery of life is founded on chiral building blocks, but no experimental technique is currently available to distinguish or monitor chiral systems in live cell bio-imaging studies. ...Luminescent chiral molecules encode a unique optical fingerprint within emitted circularly polarized light (CPL) carrying information about the molecular environment, conformation, and binding state. Here, we present a CPL Laser Scanning Confocal Microscope (CPL-LSCM) capable of simultaneous chiroptical contrast based live-cell imaging of endogenous and engineered CPL-active cellular probes. Further, we demonstrate that CPL-active probes can be activated using two-photon excitation, with complete CPL spectrum recovery. The combination of these two milestone results empowers the multidisciplinary imaging community, allowing the study of chiral interactions on a sub-cellular level in a new (chiral) light.
This communication presents a novel miniaturized circularly polarized (CP) very high frequency/ultrahigh frequency dual-band four-element sequential-rotation array antenna for SATCOM applications. ...The dual-band operation is realized by using radiation-coupled dual-L antenna as the array element. Four elements are bent and alternately overlapped in a sequential-rotation manner, which effectively reduces the array antenna's size while ensures that elements do not touch each other to maintain dual resonance. This results in a compact design which makes better use of the limited space to achieve good performances. Furthermore, since it does not rely on dielectric materials, particularly high permittivity materials, to reduce the resonance length, the proposed array antenna is both lightweight and low cost when compared with conventional miniaturized CP antennas operating at similar frequencies and having close performances. A prototype working at 295/355 MHz is designed, fabricated, and measured, whose weight is 786 g and effective size is <inline-formula> <tex-math notation="LaTeX">0.197{\lambda } \times 0.197{\lambda } \times 0.068{\lambda } </tex-math></inline-formula> at 295 MHz. The measured bandwidth of the main body for active reflection coefficient <inline-formula> <tex-math notation="LaTeX">\le -9.5 </tex-math></inline-formula> dB is 5.6 MHz (1.9%) and 7.2 MHz (2%) for the lower and higher bands, respectively. The measured gain, axial ratio, and efficiency of the proposed array antenna are better than 4.5 dBi, 1.15 dB, and 71% within ±2 MHz bandwidth for both bands.
The refractive index is one of the most basic optical properties of a material and its interaction with light. Modern materials engineering—particularly the concept of metamaterials—has made it ...necessary to consider its subtleties, including anisotropy and complex values. Here we re-examine the refractive index and find a general way to calculate the direction-dependent refractive index and the condition for zero index in a given direction. By analogy with linear versus circular polarization, we show that when the zero-index direction is complex-valued, a material supports waves that can propagate in only one sense, for example, clockwise. We show that there is an infinite family of both time-reversible and time-irreversible homogeneous electromagnetic media that support unidirectional propagation for a particular polarization. As well as extending the concept of the refractive index, shedding new light on our understanding of topological photonics and providing new sets of material parameters, our simple picture also reproduces many of the findings derived using topology.A general approach to derive direction-dependent complex refractive indices close to zero produces infinite families of time-reversible and infinite families of time-irreversible electromagnetic materials, without invoking the concept of topology.
A circular polarization (CP)-agile and continuous beam-steerable array antenna is presented using a hybrid design approach. It is accomplished by combining digital reconfigurable antenna elements ...with analog continuously tunable phase shifters. To realize both polarization reconfiguration and initial phase generation for beam scanning simultaneously, the designed antenna element enables eight states that correspond to two CP modes with four quantized phases. The phase shifters further provide additional variable phases of −90° to 0° for antenna element excitation. Superposition of the initial and additional phases helps to satisfy full and continuous 360° phase coverage for a beam-steerable array. Meanwhile, phase decomposition also facilitates the design of phase shifters without complex or cascaded structures. By altering the bias states of the electronic components loaded in the array antenna, CP switching and beam scanning can be independently controlled. For verification, prototypes of the antenna element, phase shifter, and a four-element array are all fabricated and tested. Reasonable agreement is obtained between simulation and measurement. The resultant array could scan up to nearly ±40° off the boresight, along with stable radiation patterns and good CP performance.
A compact wide-beam endfire antenna with ground radiation mode and vertically polarized mode for circular polarization (CP) is presented in this article. The antenna is constructed based on a ...configuration of coupled-mode patch antenna (CMPA), which consists of two coupling cavities with a shorting wall, and can generate vertically polarized modes. The CP is realized through a pair of orthogonally polarized modes of horizontal and vertical polarizations. Meanwhile, rendering them acquires an equal amplitude and a 90° phase difference. The horizontally polarized radiation mode is realized through inserting a crossed ground slot. Offset probe feed is used to excite all the radiation modes and introduce an additional phase shift for the CP. A set of offset ground slots (OGSs) are then applied to perturb the electromagnetic coupling of the modes and adjust the phase and magnitude of the radiating electric fields (E-fields). Several effects are synthesized, which results in a wide-beam circularly polarized (CP) endfire radiation. Aiming to improve the radiation performances, a cavity-backed planar reflector was applied in the experiment. Simulated and measured results are detailed and analyzed, which demonstrate that the measured 3 dB axial ratio (AR < 3 dB) bandwidth (ARBW) ranges from 3.385 to 3.428 GHz (1.2%), and the peak gain can be up to 3.4 dBi if the planar reflector is added. The measured half-power beamwidth (HPBW) and 3 dB ARBW can be up to 88°/114° and 53°/112° at 3.4 GHz, respectively. The antenna size (excluding the reflector) is maintained at <inline-formula> <tex-math notation="LaTeX">0.49\lambda _{0}\times 0.25\lambda _{0}\times 0.017\lambda _{0} </tex-math></inline-formula>, where <inline-formula> <tex-math notation="LaTeX">\lambda _{0} </tex-math></inline-formula> is the wavelength in free space, performing a compact configuration.
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