Hypocycloid-shaped hollow-core photonic crystal fiber Part I: Arc curvature effect on confinement loss

Abstract

We report on numerical and experimental studies showing the influence of arc curvature on the confinement loss in hypocycloid-core Kagome hollow-core photonic crystal fiber. The results prove that with such a design the optical performances are strongly driven by the contour negative curvature of the core-cladding interface. They show that the increase in arc curvature results in a strong decrease in both the confinement loss and the optical power overlap between the core mode and the silica core-surround, including a modal content approaching true single-mode guidance. Fibers with enhanced negative curvature were then fabricated with a record loss-level of 17 dB/km at 1064 nm.

Dual hollow-core anti-resonant fibres

“…This freedom opens up the potential for simpler fibre designs and large core diameters (up to ~100 μm 5 ), which provide low loss guidance over broad spectral windows and makes HC-ARFs suitable for applications such as high power delivery and gas and vapour based non-linear optics. Recent advances in the understanding of the core wall geometry in HC-ARFs and its impact on fibre attenuation 6,7 have also enabled HC-ARFs to begin to compete with HC-PBGFs in terms of fibre attenuation at short wavelengths (≤ ~1µm) and in the mid-IR 8 .…”

Optimized inhibited-coupling Kagome fibers at Yb-Nd:Yag (85 dB/km) and Ti:Sa (30 dB/km) ranges

“…Since then, much progress has been made in both understanding the entailed guidance mechanism [2] and in its transmission performance. The latter has been continuously improved since the introduction of hypocycloid core contour (i.e., negative curvature core contour) in 2010, which led, within a short period of time, to several and successive record loss figures in the visible/ near-infrared [3,5,11,16,17]. The most recent one reported presents a loss figure of 7.7 dB/km at 750 nm using tubular amorphous lattice HC-PCF [7].…”

S2 Measurement of Higher Order Mode Content in Low Loss Hypocycloid Kagomé Hollow Core Photonic Crystal Fiber

“…A scanning electron micrograph (SEM) image showing the 7 cell KHCF microstructure is shown in Fig. 1a (inset); the fiber has a ≈65 µm inner core diameter (corresponding to an estimated MFD ≈ 51 µm), ≈ 650 nm strut thickness and negative curvature parameter, b = 0.59 (as defined in [3]). The 7 cell KHCF guides over a bandwidth of ≈ 350 nm (1400 -1750 nm) with a minimum transmission loss ≈ 58 dB/km at 1541 nm.…”