Azimuthally asymmetric tubular lattice hollow-core optical fiber

A new, to the best of our knowledge, hollow-core optical fiber based on a tube lattice geometry is proposed. The fiber cross section is formed by eight tubes with five different thicknesses, and the guidance mechanism is based on the inhibited coupling phenomenon. As such, its transmittance spectrum displays low-loss windows intercalated with high-loss regions, each of the latter related to specific core-cladding modal couplings. The spectral behavior of the straight and bent waveguide is numerically analyzed. Simulations on different curvature radii and directions (angles) show the core mode displacement toward the outer side of the curvature and its impact on the spectral shift of the high-loss wavelengths. The different response of each tube resonance is investigated and discussed. The proposed structure identifies a new and promising path for the development of directional curvature sensors.