Numerical modeling of a hybrid hollow-core fiber for enhanced mid-infrared guidance

We propose a novel design of hollow-core fiber for enhanced light guidance in the mid-infrared. The structure combines an arrangement of non-touching antiresonant elements in the air core with a multilayer glass/polymer structure in the fiber's cladding. Through numerical modeling, we demonstrate that the combination of antiresonant/inhibited-coupling and photonic bandgap guidance mechanisms can decrease the optical loss of a tubular antiresonant fiber by more than one order of magnitude. More specifically, our simulations demonstrate losses of the HE₁₁ mode in the few dB/km level, which can be tuned through mid-infrared wavelengths (5 µm-10.6 µm) by carefully optimizing the structural parameters of both structures. We also show that the hybrid hollow-core fiber design is more robust to bend-induced loss than an equivalent tubular antiresonant fiber or a Bragg/OmniGuide fiber. As a result, if successfully fabricated, the hybrid hollow-core fiber will offer low-loss, high beam-quality, effectively single-mode operation, and low bending losses, potentially solving many of the problems that affect all known mid-infrared fiber types.