Science Daily July 3, 2023
Antiresonant, hollow-core optical fibers are currently challenging or even exceeding the loss performance of conventional solid-core fibers. Researchers in the UK have shown that the glass elements of the cladding structure with an approximately radial orientation play a crucial role in determining the confinement loss by strongly shaping the wave fields in the azimuthal coordinate. Azimuthal confinement can result in an evanescent field in the radial direction through the cladding, leading to a confinement loss that is substantially lower than would be the case without azimuthal confinement. They developed a comprehensive theory of azimuthal confinement, yielding an expression for the confinement loss of any fiber structure with a single antiresonant glass layer between the core and the outer glass jacket. This was tested by comparison with large-scale numerical simulations on two types of cladding structures. They showed that negative curvature of the core surround has little or no intrinsic role in reducing confinement loss in fibers with a nodeless cladding structure. In model structures the power of azimuthal confinement loss dropped by more than two orders of magnitude as the radial width of the cladding was increased. According to the researchers the concept of azimuthal confinement will be valuable in interpreting confinement loss in a wide range of existing antiresonant, hollow-core fibers and in the design of novel, low loss cladding structures… read more. Open Access TECHNICAL ARTICLEÂ
Schematic illustration of azimuthal confinement in a single-ring fiber. Credit: Optica Vol. 10, Issue 7, pp. 854-870 (2023)