Ultra-large bandwidth hollow-core guiding in all-silica Bragg fibers with nano-supports

Abstract

Abstract:We demonstrate a new class of hollow-core Bragg fibers that are composed of concentric cylindrical silica rings separated by nanoscale support bridges. We theoretically predict and experimentally observe hollow-core confinement over an octave frequency range. The bandwidth of bandgap guiding in this new class of Bragg fibers exceeds that of other hollow-core fibers reported in the literature. With only three rings of silica cladding layers, these Bragg fibers achieve propagation loss of the order of 1 dB/m. References and Links1. P. Yeh, A. Yariv, and E. Marom, "Theory of Bragg fiber," J. Opt. Soc. Am. 68, 1196-1201 (1978). 2. J. C. Knight, J. Broeng, T. A. Birks, and P. St. J. Russell, "Photonic band gap guidance in optical fibers,"Science 282, 1476-1478 (1998). 3. R. F. Cregan et al., "Single-mode photonic band gap guidance of light in air," Science 285, 1537-1539 (1999). 4. J. C. Knight, "Photonic crystal fibres," Nature 424, 847-851 (2003). 5. Y. Fink et al., "Guiding optical light in air using an all-dielectric structure," J. Lightwave Technol. 17, 2039-2041 (1999). IntroductionThe concept of hollow-core Bragg fibers, in which the fiber cladding is composed of cylindrical dielectric layers with alternating refractive indices ( Fig. 1(a) -4]. In both cases, light is confined to a central hollow-core due to Bragg reflection from the periodic cladding structure. With little overlap between the propagating modes and the cladding materials, hollow core fibers are ideal for applications involving high optical powers [5,6]. Other potential advantages include significantly reduced nonlinearity and lower propagation loss [7,8]. In addition, hollow core fibers also provide an attractive paradigm to study novel nonlinear optical phenomena in gas phase materials [9,10]. One major challenge in fabricating Bragg fibers involves the identification of dielectric materials with not only a large index contrast, but also compatible rheological and thermal properties. In this paper, we report a new class of Bragg fibers that are composed of cylindrical dielectric layers in air, separated by nanoscale support bridges. Consequently, such Bragg fibers can be constructed from a single dielectric material such as a glass or a polymer. Furthermore, they have the unique property of supporting bandgap guiding over an octave frequency range, which is much larger than what has been achieved by any other hollow-core fiber [6,7,[11][12][13][14][15]. Ideally, our theoretical calculations indicate that such hollow-core air-silica Bragg fibers can achieve confinement loss of the order of 0.1 dB/km with only four silica cladding rings. This paper is organized as follows. In section 2, we theoretically analyze the properties of hollow-core air-silica Bragg fibers and demonstrate some of the unique features of this new class of Bragg fibers. In section 3, we discuss the fabrication and the experimental characterization of the hollow-core air-silica Bragg fibers in some details. The paper is summarized in section 4.

Bandgaps and antiresonances in integrated-ARROWs and Bragg fibers; a simple model

“…1); and, from this, the construction of a simple analytic model for the analysis of the full, nontrivial, 2-D bandgap spectra of such cladding structures. Considering the first theme, fibers with a binary-layered (Bragg) cladding are well known for their ability to confine light to cores with refractive indices equal to or lower than either of the cladding indices [1][2][3][4][5][6][7][8]. Analogous types of planar waveguides known as integrated Antiresonant Reflecting Optical Waveguides (integrated-ARROWs) exhibit similar low-index confinement behaviour [9][10][11][12][13] but are typically treated as distinct to Bragg waveguides and their associated bandgap guidance mechanism.…”

“…For our second theme, it has recently been shown [23] that in single-material Bragg fibers [5,23,24] (hollow level-core waveguides) a new class of large bandwidth bandgaps are available, hence also available to any level-core layered-cladding waveguide (Fig. 1).…”

“…We demonstrate how our model can determine a number of nontrivial properties with simple, fully analytic, expressions. Such tools are indispensable for the understanding and design of depressedcore layered-cladding waveguides, whether they be fibers (multi-dielectric, such as the aforementioned hollow-core Bragg fibers [3,4,6], or single-material Bragg fibers [5,23,24]) or integrated-ARROWs [9][10][11][12][13]. We thus expect that the SPARROW model will be particularly useful for the design of layered-cladding waveguides with gas or liquid cores for applications in sensing, microfluidics, and novel nonlinear waveguides.…”

Photonic Crystal Fibre for Dispersion Controll

“…4.1. This type of fibre is intended to combine the advantageous property of Bragg fibres with extra broad bandgaps and the light guidence in a low nonlinearity hollow core region (Vienne et al, 2004). Due to the significance of small details in PBG structures which are crucial in the design of reliable PBG waveguides, a more accurate model is presented with a honey-comb cladding structure in Sec.…”

Progress in the Fabrication of the Next-Generation Soft Glass Microstructured Optical Fibers

“…This fiber type is of great interest for photonic bandgap fibers [16]. We fabricated preforms and fibers using F2 and bismuth glass.…”