Low loss and broadband hollow-core photonic crystal fibers

We report on recent developments on fabrication and optical guidance of Kagome-lattice hollow-core photonic crystal fiber (HC-PCF). These include the design and fabrication of a hypocycloid-shaped core Kagome HC-PCF that combines a record optical attenuation with a baseline exhibiting similar to 180 dB/km over a transmission bandwidth larger than 200 THz. These results are corroborated with theoretical simulations which show that both the core-shape and the cladding ring number play role in inhibited coupling, inducing core-mode confinement for the fundamental transmission band. We also show that the inhibited coupling is weaker for the first higher-order transmission band by theoretically and experimentally comparing Kagome HC-PCF with a single anti-resonant ring hollow-core fiber.