Soft photonic crystals are appealing due to their self-assembly ability, wide tunability, and multistimuli-responsiveness. However, their response time is relatively slow, ranging from milliseconds to minutes. Here, we report submicrosecond switching of chiral liquid crystals (LCs) with 1D photonic microstructures, where electric fields modify the orientational order of molecules and quench their fluctuations, rather than altering the orientation. Thus, the adjusted refractive indices result in a fast shift of the photonic bandgap, on the order of 100 ns, which is four orders of magnitude faster than conventional electro-optic switching in cholesterics. This work offers tremendous opportunities for soft photonic applications.

Circularly polarized luminescent (CPL) materials have received significant attention in the field of fundamental science recently. These materials offer substantial advancement of technological applications, such as optical data storage, displays, and quantum communication. Various strategies have been proposed in self‐assembled materials consisting of inorganic, organic, and hybrid systems, particularly in the chiral orientationally ordered soft matter systems (e.g., chiral liquid crystals (LCs) and LC polymers). However, developing scientific approaches to achieve the pronounced and steerable circularly polarized light emission remains challenging. Herein, we present a comprehensive review on the recent development of CPL materials based on chiral LCs, including thermotropic LCs (cholesteric LCs and bent‐core LCs), lyotropic LCs (nanocellulose LCs and polyacetylene‐based LCs), and LC polymers (cholesteric LC‐based polymers, helical nanofibers, and helical network). In addition, the fundamental mechanisms, design principles, and potential applications based on these chiral LCs and LC polymers in soft matter systems are systematically reviewed. This review summarizes with a prospect on the latent challenges, which can strengthen our understanding of the basic principles of CPL in chiral orientationally ordered soft matter systems and provide a new insight into the progress in several fields, such as chemistry, materials science, optics, electronics, and biology.

Electric fields modify the optical properties of nematic liquid crystals (NLCs) by changing the nematic molecular orientation or order parameters, which enables electro-optic applications of NLCs. However, the field-induced optic change is undesirable in some cases. Here, we experimentally demonstrate that polymer stabilization weakens the birefringence change of NLCs caused by the nanosecond electrically modified order parameter effect. The birefringence change is reduced by 65% in the NLC doped with 25% reactive monomer, which is polymerized close to the nematic-to-isotropic phase transition. This technique could be used in liquid crystal devices where the birefringence change is unfavored.

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