Waveguiding mechanism in tube lattice fibers

Abstract

Waveguiding mechanism and modal characteristics of hollow core fibers consisting of a single or a regular arrangement of dielectric tubes are investigated. These fibers have been recently proposed as low loss, broadband THz waveguides. By starting from a description in terms of coupling between air and dielectric modes in a single tube waveguide, a simple and useful model is proposed and numerically validated. It is able to predict dispersion curves, high and low loss spectral regions, and the conditions to ensure the existence of low loss regions. In addition, it allows a better understanding of the role of the geometrical parameters and of the dielectric refractive index. The model is then applied to improve the tradeoff between low loss and effectively single mode propagation, showing that the best results are obtained with a heptagonal arrangement of the tubes.

Hollow-core fibers for high power pulse delivery

“…To achieve HOM suppression in a large core (>20µm) HC fibers a well-known method is to exploit resonant coupling to cladding modes [17]. A previous publication [18] analyses a similar situation for AR-HC fiber made of teflon, at terahertz wavelengths and touching tubes. The numerical analysis done here is consistent with their findings and represents an extension to fibers with non-touching tubes.…”

“…The numerical analysis done here is consistent with their findings and represents an extension to fibers with non-touching tubes. The use of a large number of tubes (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) would greatly limit bend loss in this kind of fiber as shown in [13]. On the other hand it would limit the maximum obtainable ratio d/D, consequently limiting the suppression of HOM as described in the following.…”

Broadband high birefringence and polarizing hollow core antiresonant fibers

“…guided inside the tubes) modes. Based on the similarity of the guidance mechanism in NANFs and in simpler hollow core fibers made of a borehole in glass, it is possible to calculate the necessary geometrical specifications to match the index of the core and cladding modes [41] …”

Transmission of CO2 Laser Radiation Through Glass Hollow Core Microstructured Fibers

“…All calculations will be made in the narrow spectral region near λ = 10.6 µm. This fact is connected with high density of the individual capillary eigenstates (leaky modes with high azimuthal indices [Vincetti & Setti, 2010]) which occur at such high values of the glass refractive indices and individual capillary dimensions with respect to the wavelength. We will show that the way of obtaining a low loss waveguide regime in the glass HC MFs with the cladding consisting of capillaries presents a complicated multiparameter task.…”