Inhibited-coupling guiding hollow core photonic crystal fibers

Summary form only given. Two major classes of hollow-core Photonic crystal fibres (HC-PCF) have emerged in the last decade. The first one relies on a cladding exhibiting a photonic bandgap in an appropriate index-frequency space. The salient features of these PBG guiding HC-PCF (PBG HC-PCF) are a relatively low transmission loss and a limited optical bandwidth. The second one guides over a large optical bandwidth via a mechanism akin to the formation of Von-Neumann-Wigner quasi-bound states in a continuum, and whereby the coupling between the cladding modes and the core modes is strongly inhibited. Until recently, in this inhibited-coupling (IC) guiding HC-PCF (IC HC-PCF) the transmission loss figures have remained at levels that are much higher than what is achievable in PBG HC-PCF. However, a radical improvement in the IC HC-PCF transmission performance was achieved with the introduction of hypocycloid core-shape and where loss figures are as low as 30-40 dB/km in the telecom spectral range and in the mid-IR. Here we review on the recent development on IC guiding HC-PCF and on the physical principles that led to the unique combination of record loss figures, quasi-single mode operation and very low dispersion. Furthermore, the intrinsic property of IC optical guidance implies the decrease in confinement loss goes hand in hand with the decrease in the optical overlap of the guide core mode and the silica surround. As a result demonstration of large energy transportation was demonstration in both the nanosecond and femtosecond duration pulses with strong compression ratios.