Tunable Topological Lasing of Circularly Polarized Light in a Soft-Matter-Based Superlattice

The advance of topological photonics has heralded a revolution for manipulating light as well as for the development of novel photonic devices such as topological insulator lasers. Here, the robust topological interface state lasing in a polymer-cholesteric liquid crystal superlattice at the visible regime is demonstrated. By use of the femtosecond-laser direct-writing and self-assembling techniques, the micron-sized superlattice is established with a controlled mini-band structure and a topological interface defect, thereby achieving a low threshold for robust topological lasing at about 0.4 mu J (722 W center dot mm(-2)). Thanks to the chiral liquid crystal, not only is the circularly polarized lasing readily achieved, but the emission wavelength is thermally tuned. The results bring about the possibility to realize tunable, circularly polarized, compact, and integrated topological photonic devices at low cost, as well as to engineer an ideal platform for exploring topological physics that involves light-matter interaction in soft-matter environments.