ある中空コア光ファイバーが他の光ファイバーよりも効率的である理由を理論的に理解することで、新しい低損失光ファイバーの設計がひらめく。 A theoretical understanding of what makes some hollow-core optical fibres more efficient than others will inspire the design of new low-loss fibres.
2023-07-03 バース大学
◆彼らの理論的および計算的な分析により、ガラス繊維を組み込んだ中空中心の光ファイバーが光の損失を非常に低く保つメカニズムが明らかになりました。この研究は、光ファイバーの設計において光の損失を最小限にする新しいアプローチを提供し、今後の研究や新しいデザインの開発に活かされることが期待されています。
＜関連情報＞
- https://www.bath.ac.uk/announcements/limiting-loss-in-leaky-fibres/
- https://opg.optica.org/optica/fulltext.cfm?uri=optica-10-7-854&id=532405
方位角閉じ込め：反共振中空コアファイバーの閉じ込め損失を理解する上で欠けている要素 Azimuthal confinement: the missing ingredient in understanding confinement loss in antiresonant, hollow-core fibers
Leah R. Murphy and David Bird
Optica Published: June 30, 2023
DOI:https://doi.org/10.1364/OPTICA.492058
Abstract
Antiresonant, hollow-core optical fibers are currently challenging or even exceeding the loss performance of conventional solid-core fibers. Despite this progress, there are aspects of the guidance mechanism in these fibers that are still not understood. For example, a physical mechanism to explain why negative curvature of the core surround is correlated with low loss remains elusive. It is 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. This shaping, described as azimuthal confinement, can result in an evanescent field in the radial direction through the cladding, and this leads to a confinement loss that is substantially lower than would be the case without azimuthal confinement. A comprehensive theory of azimuthal confinement is developed, 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 is tested by comparison with large-scale numerical simulations on two types of cladding structure. It is shown that negative curvature of the core surround has little or no intrinsic role in reducing confinement loss in fibers with a nodeless cladding structure. The power of azimuthal confinement is demonstrated in model structures where the confinement loss drops by more than two orders of magnitude as the radial width of the cladding is increased. It is anticipated that 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.
