Recent breakthroughs in hollow core fiber technology

Flexible dielectric optical fibers guiding light in a hollow core were conceptually imagined at the end of the 19th century, but first demonstrated in practice about 2 decades ago. Since then, many geometric variants have been described and implemented, and theoretical models developed and finessed. Despite this, for a fairly long time the key metric by which their performance was judged – attenuation – has remained quite considerably higher than standard all-glass fibers. In this paper, we describe the recent breakthroughs in hollow core fiber technology. We trace the story of this breakthrough from the theoretical exploration of a new design of hollow core fiber, through early implementations, up to the staggering results achieved over the last 18 months. The progress reported concerns not only a reduction in the fiber attenuation level, but also a considerable improvement in modal quality of the fibers, which have led to excellent data transmission performance. These fabricated fibers tell a story of improvements in all aspects of the technology, including preform preparation, performance modelling, fiber draw dynamics and coatings.