ABSTRACT
The photonic spin Hall effect (PSHE), manifesting itself as the spin-dependent shifts of left- and right-handed circularly polarized light beams, holds potential applications in nanophotonics and precision measurement. Thus, realizing effective enhancement and regulation of PSHE is highly desirable. It is known that by adjusting the Fermi energy of graphene, the spin shifts in a graphene-based optical structure can be actively modulated and amplified. However, this method generally works in a very narrow range of incident angles (near Brewster's angle) and the incident state is limited to the horizontal polarization. In this Letter, we address these issues by theoretically proposing a feasible way to amplify and control the PSHE in a wide range of incident angles by modulating the Fermi energy when the light beam is reflected at a quasi-PT-symmetric structure (gain-loss medium embedded with monolayer graphene). Interestingly, we reveal that the electrically tunable PSHE can be achieved for both horizontal and vertical polarizations near the quasi-exceptional points (quasi-EPs). Moreover, we can directly determine the tiny variation of the Fermi energy by observing the field distribution of a single circularly polarized component in this structure without using the weak measurements.
ABSTRACT
Directional water transport that occurs in natural insects and plants is important to both organisms and advanced science and technology. Despite the many studies conducted to facilitate directional liquid transport by constructing double-layered hydrophilic/hydrophobic materials, it remains difficult to achieve continuous water transport and reduce liquid wastage due to the hydrophilic regions. Herein, a directional water transport fabric (DWTF) was fabricated using a simple single-side coating method based on entirely hydrophobic materials. With coating thicknesses of 13-29 µm, the fabric could guide the continuous water motion from the coated to the uncoated side and can be utilized as a "liquid diode". In addition, the DWTF exhibited a water wastage reduction during the transport process, benefiting from the intrinsic hydrophobic properties of the material. Moreover, a plausible mechanism of water transport is proposed to explain the water droplet transfer in the bilayered hydrophobic materials. Consequently, the resulting DWTF exhibited an excellent accumulative one-way transport capability (AOTC) of 965.7% and a desirable overall moisture management capability (OMMC) of 0.92. This work provides an avenue for fabricating smart fluid delivery materials to various applications such as flexible microfluidics, wound dressing, oil-water separation processes, and engineered desiccant materials.
