Low-loss hollow-core fibers with improved single-modedness

Abstract

Hollow-core fibers (HCFs) are a revolution in light guidance with enormous potential. They promise lower loss than any other waveguide, but have not yet achieved this potential because of a tradeoff between loss and single-moded operation. This paper demonstrates progress on a strategy to beat this tradeoff: we measure the first hollow-core fiber employing Perturbed Resonance for Improved Single Modedness (PRISM), where unwanted modes are robustly stripped away. The fiber has fundamental-mode loss of 7.5 dB/km, while other modes of the 19-lattice-cell core see loss >3000 dB/km. This level of single-modedness is far better than previous 19-cell or 7-cell HCFs, and even comparable to some commercial solid-core fibers. Modeling indicates this measured loss can be improved. By breaking the connection between core size and single-modedness, this first PRISM demonstration opens a new path towards achieving the low-loss potential of HCFs.

Hollow-core photonic bandgap fibers: technology and applications

“…Due to a higher overlap with the air-glass interfaces, the LP 11a,b modes were found to have a higher scattering loss than the LP 01 (7.4 ± 0.8 dB/km vs. 3.3 ± 0.8 at 1550 nm, respectively, see Figure 10A), in agreement with modelling expectations [57]. An altogether different approach to managing the higher mode content is to actively suppress it via resonant coupling to secondary cores located in the cladding [71]. The PRISM fibre, developed by OFS Labs, contains a 19 cell central core with two 7 cell secondary cores diametrically located about it, which provide a > 400 times increase in the differential loss of all higher order modes and which ensures close to strictly single mode operation despite the large core.…”

“…HC-PBGFs offer potential benefits on all of these fronts and as a consequence various groups are looking to realise these benefits in practice [123]. Recent work on large core HC-PBGFs with effectively single mode behaviour based on resonant stripping of higher-order modes looks particularly promising for these applications [71].…”

Revolver Hollow Core Optical Fibers

“…In the figure legend, the plotted experimental data are indexed by numbers in round brackets followed by references to literature in square brackets. More details are given in the text [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. [36] and in chalcogenide fibers at a wavelength of up to 6.5 µm [37,38].…”

Extruded single ring hollow core optical fibers for Raman sensing

“…[1][2][3] The most widespread category of such fibers is hollow core photonic crystal fibers (HC-PCF), where the guiding mechanism relies on a large number of sub-wavelength features periodically arranged around the hollow core, making them costly and difficult to fabricate by capillary stacking. 4,5 Antiresonance guiding fibers, where optical guiding is achieved by Fabry-Perot reflection off the walls of a waveguide, in the simplest case a thin capillary suspended inside an outer thicker jacket, have emerged as a category of fibers that combines the advantages of HC-PCFs with simpler fabrication, 6 resulting in geometries such as a single suspended ring 7,8 and negative radius of curvature hollow cores structures. 9 The advantages of these fibers have made them interesting platforms for a range of chemical and biological sensing applications.…”