Effectively single high-order mode guidance based on selective mode filtering

Compared with the fundamental mode in the optical fibers, the higher-order modes with unique dispersion characteristics give the radiation generated by nonlinearity a wider bandwidth. On this basis, a design scheme of single-mode operation in a few-mode optical fiber is proposed. All the core modes except the LP 02 mode will be filtered out by introducing two microstructure cladding regions that are strongly coupled to the core modes with different refractive indexes. The simulation results show that the loss of the LP 02 mode is less than 0.1 dB/m in the bandwidth greater than 20 nm, while the losses of other modes are greater than 10 dB/m, indicating that the fiber achieves effective transmission of a single high-order mode. This work broadens the concept of selective mode filtering design and may attract more researchers’ attention to single high-order mode fiber applications. Graphical abstract