Unusual properties of hollow-core fibres

Hollow core optical fibres have many unique properties, especially compared to traditional glass-core optical fibres [1]. Firstly, the light path is accessible and light can thus interact with the gas inside over long lengths, making them interesting for applications in gas sensing or for nonlinear processes in gasses. Hollow core fibres can also operate at wavelengths, where silica glass has poor transmission and their chromatic dispersion is not compromised by the chromatic dispersion of bulk glass. Yet another unique feature is weak interaction of light with the guiding medium (typically air), significantly increasing the damage threshold and thus making them a good candidate for high-power (average or peak power) light delivery. Another group of unique features is related to how their properties (little) change with temperature. In the presentation, we will firstly show where the common fibre optics wisdom (gained from work with standard optical fibres) tends to fail. In the second part, we will discuss how differently hollow core fibre change with temperature as compared to standard optical fibres and how it can be used for various applications, including fibre interferometry and time-stable signal transmission.