Leakage channels enabled multi-resonant all-solid photonic bandgap fiber for effective single-mode propagation

Large mode-area all-solid anti-resonant fiber based on chalcogenide glass for mid-infrared transmission

A large mode-area chalcogenide all-solid anti-resonant fiber has been designed and successfully prepared for the first time. The numerical results show that the high-order mode extinction ratio of the designed fiber can reach 6000, and the maximum mode-area is 1500 um². The fiber possesses a calculated low bending loss of less than 10^-2dB/m as the bending radius is larger than 15 cm. In addition, there is a low normal dispersion of -3 ps/nm/km at 5 μm, which is beneficial for the transmission of high power mid-infrared laser. Finally, a completely structured all-solid fiber was prepared by the precision drilling and two-stage rod-in-tube methods. The fabricated fibers transmit in the mid-infrared spectral range from 4.5 to 7.5 μm with the lowest loss of 7 dB/m @ 4.8 μm. Modeling suggests that the theoretical loss of the optimized structure is consistent with that of the prepared structure in the long wavelength band.

Advances in Silica-Based Large Mode Area and Polarization-Maintaining Photonic Crystal Fiber Research

In recent years, photonic crystal fibers (PCFs) have attracted increasing attention. Compared with traditional optical fibers, PCFs exhibit many unique optical properties and superior performance due to their high degree of structural design freedom. Using large-mode area (LMA) fibers with single-mode operation is essential to overcoming emerging problems as the power of fiber lasers scales up, which can effectively reduce the power density and mitigate the influence of nonlinear effects. With a brief introduction of the concept, classification, light transmission mechanism, basic properties, and theoretical analysis methods of PCFs, this paper mainly compiles the worldwide development of large-mode area and polarization-maintaining (PM) PCFs, and finally proposes possible technical routes to realize the single-mode operation of LMA-PCFs and PM-LMA-PCFs. Finally, the future development prospects of the PCFs are discussed.