Spintronics employs the spin of electrons to encode information. Akin to spintronics, valleytronics exploits the valley as pseudospin‐carrying controllable binary information. 2D transition metal dichalcogenides (TMDCs) have asymmetric +K and −K valleys. The valley pseudospins of these materials can be manipulated by selective pumping, giving rise to valley‐dependent circularly polarized photoluminescence. The photonic spin–orbit interactions (SOIs) in nanophotonic systems allow the transformation or coupling of optical spin angular momentum to orbital angular momentum of light. Hybridizing 2D TMDC electronic systems with nanophotonic systems can open up an avenue for merging TMDC valley polarization and photonic SOIs to uncover new mechanisms of on‐chip optical information processing and transport. This review focuses on the fundamentals and implications of TMDC valley polarization, photonic SOI effects, and their chiral coupling in hybrid TMDCs–nanophotonic systems. First, the deterministic valley‐dependent optical properties of TMDCs and recent efforts in achieving large valley polarization contrast are reviewed. Then, various SOI effects in nanophotonic systems and their physical mechanisms are summarized. At the end, recent demonstrations of chiral coupling between TMDC valley excitons and light through spin‐direction locking at hybrid interfaces are highlighted.

The development of chiral photoluminescence (PL) has drawn extensive attention owing to its potential applications in optical data storage, biosensing, and displays. Due to the lack of effective synthesis methods, colloidal metal nanostructures with intrinsic chiral PL have rarely been reported. Herein, the chiral excitation and emission properties of single gold nanohelicoids (GNHs) are reported for the first time. By measuring their circular dichroism (CD) response and excitation/emission polarizationresolved PL spectra, it is revealed that the intrinsic chirality arising from the geometric handedness of the GNHs induces the observed excitationpolarization-correlated chiral PL. Two models are developed to analyze the observed circular-polarization-steered effect: (1) a chiral PL phenomenological model quantitatively reproduces the PL dissymmetry features; (2) a chiral Purcell effect model reveals that the super-chiral near fields in the GNHs account for the far-field chiral responses such as the polarization-steered chiral PL. The findings not only provide an important understanding of the physical mechanism responsible for luminescent chiral plasmonic nanostructures, but also expand the research on chiral PL-active materials from achiral/chiral hybrid systems to metallic nanostructures with intrinsic structural chirality, thereby broadening the scope of applications in 3D chiral imaging and sensing as well as microstructure analysis.

Valley-dependent excitation and emission in transition metal dichalcogenides (TMDCs) have recently emerged as a new avenue for optical data manipulation, quantum optical technologies, and chiral photonics. The valleypolarized electronic states can be optically addressed through photonic spin−orbit interaction of excitonic emission, typically with plasmonic nanostructures, but their performance is limited by the low quantum yield of neutral excitons in TMDC multilayers and the large Ohmic loss of plasmonic systems. Here, we demonstrate a valleytronic system based on the trion emission in high-quantum-yield WS 2 monolayers chirally coupled to a low-loss microfiber. The integrated system uses the spin properties of the waveguided modes to achieve longrange directional routing of valley excitations and also provides an approach to selectively address valley-dependent emission from different spatial locations around the microfiber. This valleytronic interface can be integrated with fiber communication devices, allowing for merging valley polarization and chiral photonics as an alternative mechanism for optical information transport and manipulation in classical and quantum regimes.

The study of chiral photoluminescence in colloidal metal nanostructures extends photoluminescence research to the chiral realm and can enable a deep understanding of optical chirality. In article number 2101502, Dangyuan Lei and co‐workers report the chiral excitation and emission properties of single gold nanohelicoids (GNHs) with intrinsic structural chirality. Single GNHs exhibit polarization‐steered chiral photoluminescence under circular polarized excitation, and attribute this observation to the chiral Purcell effect.