Supercontinuum generation in second-order topological fibers composed of hexagonal chalcogenide photonic crystals

Topological photonics has attracted much attention in the community of photonics due to the fundamental and practical significances. Recently, topological photonic crystal fibers (PCFs) have been proposed as a new category of photonic topological systems, while the investigations in this direction are still at an early stage, only dealing with linear effects. This work theoretically demonstrates supercontinuum (SC) generation with waveguiding corner modes in topological fibers composed of hexagonal holey photonic crystals of chalcogenide material. The proposed topological PCF has high nonlinearity due to the small mode area and high material nonlinearity, enabling octave-spanning SC generation with low pump energy at the central wavelength of 1550 nm. The topological PCFs exhibit the dispersion characteristics and SC spectra which are immune to the structural defects, contrary to the non-topological ones. The results presented in this work pave the way towards nonlinear fiber optics with structural defects-immune performances.