Understanding origin of loss in large pitch hollow-core photonic crystal fibers and their design simplification

Abstract

It is now commonly accepted that, in large pitch hollow-core 'kagomé' lattice fibers, the loss spectrum is related to resonances of the thin silica webs in the photonic crystal cladding. Moreover, coherent scattering from successive holes' layers cannot be obtained and adding holes' layers does not decrease the loss level. In this communication, cross-comparison of experimental data and accurate numerical modeling is presented that helps demonstrate that waveguiding in large pitch hollow-core fibers arises from the antiresonance of the core surround only and does not originate from the photonic crystal cladding. The glass webs only mechanically support the core surround and are sources of extra leakage. Large pitch hollow-core fibers exhibit features of thin walled and thick walled tubular waveguides, the first one tailoring the transmission spectrum while the second one is responsible for the increased loss figure. As a consequence, an approximate calculus, based on specific features of both types of waveguides, gives the loss spectrum, in very good agreement with experimental data. Finally, a minimalist hollow-core microstructured fiber, the cladding of which consists of six thin bridges suspending the core surround, is proposed for the first time.

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].…”

Low Loss Antiresonant Hollow Core Fibres

“…Hollow core Kagome'-type fibres are ideally suited for these applications but they do present an extended complex-to-make cladding [1]. Simplified hollow core fibre types guiding by antiresonance, made of a single ring of holes around the core and presenting low loss for device applications were recently reported [2][3][4]. Here we study loss mechanisms in these fibres and present an improved fibre design with a minimum loss below 1 dB/m in the near infrared.…”

Low-loss single-mode hollow-core fiber with anisotropic anti-resonant elements

“…low-loss transmission. The absolute amount of loss of the core modes will then depend on inhibited coupling between the core and cladding modes due to a low density of cladding modes [18][19][20][21], which is a property that can be controlled by suitable fiber design engineering. Loss is further reduced in a "node-free" design [16], where the cladding tubes do not touch each other so the core mode no longer couples to the glass cladding mode in the nodal intersections.…”