Circularly Polarized Photodetectors Based on Chiral Materials: A Review

Circularly polarized light (CPL) plays an important role in many photonic techniques, including tomographic scanning based on circular polarization ellipsometry, optical communication and information of spin, and quantum-based optical calculation and information processing. To fully exploit the functions of CPL in these fields, integrated photoelectric sensors capable of detecting CPL are essential. Photodetectors based on chiral materials can directly detect CPL due to their intrinsic optical activity, without the need to be coupled with polarizers and quarter-wave plates as in conventional photodetectors. This review summarizes the recent research progress in CPL photodetectors based on chiral materials. We first briefly introduce the CPL photodetectors based on different types of chiral materials and their working principles. Finally, current challenges and future opportunities in the development of CPL photodetectors are prospected.

Genetic engineering of Pseudomonas chlororaphis Lzh-T5 to enhance production of trans-2,3-dihydro-3-hydroxyanthranilic acid

Trans-2,3-dihydro-3-hydroxyanthranilic acid (DHHA) is a cyclic β-amino acid used for the synthesis of non-natural peptides and chiral materials. And it is an intermediate product of phenazine production in Pseudomonas spp. Lzh-T5 is a P. chlororaphis strain isolated from tomato rhizosphere found in China. It can synthesize three antifungal phenazine compounds. Disruption the phzF gene of P. chlororaphis Lzh-T5 results in DHHA accumulation. Several strategies were used to improve production of DHHA: enhancing the shikimate pathway by overexpression, knocking out negative regulatory genes, and adding metal ions to the medium. In this study, three regulatory genes (psrA, pykF, and rpeA) were disrupted in the genome of P. chlororaphis Lzh-T5, yielding 5.52 g/L of DHHA. When six key genes selected from the shikimate, pentose phosphate, and gluconeogenesis pathways were overexpressed, the yield of DHHA increased to 7.89 g/L. Lastly, a different concentration of Fe3+ was added to the medium for DHHA fermentation. This genetically engineered strain increased the DHHA production to 10.45 g/L. According to our result, P. chlororaphis Lzh-T5 could be modified as a microbial factory to produce DHHA. This study laid a good foundation for the future industrial production and application of DHHA.

Chiroptical Metasurfaces: Principles, Classification, and Applications

Chiral materials, which show different optical behaviors when illuminated by left or right circularly polarized light due to broken mirror symmetry, have greatly impacted the field of optical sensing over the past decade. To improve the sensitivity of chiral sensing platforms, enhancing the chiroptical response is necessary. Metasurfaces, which are two-dimensional metamaterials consisting of periodic subwavelength artificial structures, have recently attracted significant attention because of their ability to enhance the chiroptical response by manipulating amplitude, phase, and polarization of electromagnetic fields. Here, we reviewed the fundamentals of chiroptical metasurfaces as well as categorized types of chiroptical metasurfaces by their intrinsic or extrinsic chirality. Finally, we introduced applications of chiral metasurfaces such as multiplexing metaholograms, metalenses, and sensors.

Crystalline chirality and interlocked double hourglass Weyl fermion in polyhedra-intercalated transition metal dichalcogenides

Introducing crystalline chirality into transition metal dichalcogenides (TMDs) has attracted much attention due to its modulation effect on optical properties and the potential to reveal new forms of electronic states. Here, we predict a number of chiral materials by intercalating polyhedra into TMD lattices, finding a type of double hourglass Weyl fermion interlocked with crystalline chirality. The best candidate RhV3S6 (P6322) possesses the largest hourglass energy window of ~380 meV, as well as strong optical circular dichroism (CD) in the infrared regime, both of which are tunable by external strains. The chirality is originally induced by the configuration of intercalated polyhedra and then reduced by the rotational atomic displacements triggered by intercalation, as indicated by CD calculations. Our study opens the way of designing chiral materials with spin-split double hourglass Weyl fermions via structural unit intercalation in achiral crystals for future chiral-functionalized optoelectronic and spintronic devices.

Generalizing the Chiral Self-Assembly of Spheres and Tetrahedra to Non-Spherical and Polydisperse Molecules in (C70)x(C60)(1-x)(SnI4)2

We describe the spontaneous chiral self-assembly of C₇₀ with SnI₄ as well as a mixture of C₆₀ and C₇₀ with SnI₄. Macroscopic single crystals with the formula (C₇₀)_x(C₆₀)_1-x(SnI₄)₂ (x = 0-1) are reported. C₆₀, which is spherical, and C₇₀, which is ellipsoidal, form a solid solution in these crystals, and the cubic lattice parameter of the chiral phase linearly increases as x grows from 0 to 1 in accordance with Vegard’s law. Our results demonstrate that nonspherical particles and polydispersity are not an impediment to the growth of chiral crystals from high-symmetry achiral precursors, providing a route to assemble achiral particles including colloidal nanocrystals and engineered nanostructures into chiral materials without the need to use external templates.<br>

Generalizing the Chiral Self-Assembly of Spheres and Tetrahedra to Non-Spherical and Polydisperse Molecules in (C70)x(C60)(1-x)(SnI4)2

We describe the spontaneous chiral self-assembly of C₇₀ with SnI₄ as well as a mixture of C₆₀ and C₇₀ with SnI₄. Macroscopic single crystals with the formula (C₇₀)_x(C₆₀)_1-x(SnI₄)₂ (x = 0-1) are reported. C₆₀, which is spherical, and C₇₀, which is ellipsoidal, form a solid solution in these crystals, and the cubic lattice parameter of the chiral phase linearly increases as x grows from 0 to 1 in accordance with Vegard’s law. Our results demonstrate that nonspherical particles and polydispersity are not an impediment to the growth of chiral crystals from high-symmetry achiral precursors, providing a route to assemble achiral particles including colloidal nanocrystals and engineered nanostructures into chiral materials without the need to use external templates.<br>

Chiral and Robust Zr(IV)-Based Metal-Organic Frameworks Built from Spiro Skeleton

Chiral metal-organic frameworks (CMOFs) have emerged as an important subclass of chiral materials; however, their development is restrained substantially by limited enantiopure functional linkers and poor chemical stabilities. Here we...