Hollow-core mode propagation in an isomeric nested anti-resonant fiber

We present a modified fiber model based on the nested hollow core anti-resonant fiber that enables the stable transmission of the orbital-angular-momentum mode HE₂₁. By replacing a pair of nested anti-resonant tubes in the horizontal axis with resonant tubes, the coupling between core mode and cladding mode has been increased. Therefore, the relative strength of fundamental mode HE₁₁ and the first higher mode HE₂₁ has been modified. The numerical simulation results indicate that the loss ratio of the lowest loss HE₁₁ to HE₂₁ can be optimized to more than 187, while the HE₂₁ still maintains a low confinement loss as 0.0027 dB/m. Our research has brought about a solution of low loss hollow core mode propagation in optical fiber. Those properties will make this fiber an ideal medium for blue-detuned atomic guidance.