Coherent control of negative refraction based on local-field enhancement and dynamically induced chirality

This paper studies the electromagnetic response of a coherently driven dense atomic ensemble to a weak probe. It finds that negative refraction with little absorption may be achieved in the presence of local-field enhanced interaction and dynamically induced chirality. The complex refractive index governing the probe refraction and absorption depends critically on the atomic density, the steady population distribution, the coherence dephasings, and the frequency de- tunings, and is also sensitive to the phase of the driving field because the photonic transition paths form a close loop. Thus, it can periodically tune the refractive index at a fixed frequency from negative to positive values and vice versa just by modulating the driving phase. Moreover, the optimal negative refraction is found to be near the probe magnetic resonance, which then requires the electric fields of the probe and the drive being on two-photon resonance due to the dipole synchronisation.

Mesomorphic Characteristics of Induced Chiral Nematic Phase of[Smectic LCP,PS(4BC/DM)/Nematic LC,E7/Chiral Dopant,CB-15]-Ternary Composite System

The phase transition behavior and aggregating states of [smectic LCP, PS(4BC/DM)/nematic LC, E7/chiral dopant, CB-15] ternary composite system were investigated on the basis of differential scanning calorimetry (DSC) measurement, polarizing optical microscopy (POM) observation and wide angle X-ray diffraction (WAXD) patterns. It was demonstrated that if the weight ratio of the chiral dopant was fixed as 4.8wt%, an induced chiral nematic (N^(*)) phase existed in the ternary system when PS(4BC/DM) ratio was below 47.6 wt%. Moreover, smectic like long range ordering appeared in the induced N^(*) phase in a certain temperature range just above the smectic A(S_(A))-N^(*) phase transition when PS(4BC/DM) ratio was between 19.1wt% and 47.6wt%.

Study on Bicoordination Chiral Inducement Catalysis of (R)-4-Thiazolidinecarboxylic Acid

The bicoordination chiral inducement catalysis of (R)-4-thiazolidinecarboxylic acid inthe enantioselective borane reduction of prochiral ketones has been studied. The fact that theabsolute configuration of the main product can be changed by simply using different operationmethods was firstly verified. And the reason of bicoordination chiral inducement was discussed.

Preparation of optical active polydiacetylene through gelating and the control of supramolecular chirality

Achiral diacetylene 10,12-pentacosadinoic acid (PCDA) and a chiral low-molecular-weight organogelator could form co-gel in organic solvent and it could be polymerized in the presence of Zn(II) ion or in the corresponding xerogel under UV-irradiation. Optically active polydiacetylene (PDA) were subsequently obtained. Supramolecular chirality of PDA could be controlled by the chirality of gelators. Left-handed and right-handed helical fibers were obtained by using Land D-gelators in xerogels respectively, and CD spectra exhibited mirror-image circular dichroism. The PDA in xerogel exhibited typical blue-to-red transition responsive to the temperature and pH, while the supramolecular chirality of PDA showed a corresponding change.

Strong circularly polarized luminescence from quantum dots/2D chiral perovskites composites

Chiral perovskites(CPs)have attracted enormous attentions since they have combined chirality and optoelectrical properties well which is promising in circularly polarized luminescence(CPL)application and of great importance for future spin-optoelectronics.However,there is a key contradiction that in chiral perovskites chirality distorts the crystal structure,leading to poor photoluminescence(PL)properties.Achieving the balance between chirality and PL is a major challenge for strong CPL from chiral perovskites.Differently,two-dimensional(2D)chiral perovskite has shown fascinating chiral induced spin selectivity(CISS)effect which can act as spin injector under ambient conditions.Here,we propose an effective strategy to achieve high CPL activity generated from quantum dots(QDs)by introducing 2D chiral perovskite as a chiral source,providing spin polarized carriers through the CISS effect.The as-synthesized QDs/CP composites exhibit dissymmetry factors(glum)up to 9.06×10^(−3).For the first time,we performed grazing incident wide angle X-ray scattering(GIWAXS)measurements,showing the chirality originates from the distorted lattices caused by the large chiral organic cations.Besides,time-resolved PL(TR-PL)measurements verify the enhanced CPL activity should be attributed to the charge transport between two components.These findings provide a useful method to achieve CPL in QDs/2D chiral perovskite heterojunctions which could be promising in spinoptoelectronics application.