Pressure-assisted melt-filling and optical characterization of Au nano-wires in microstructured fibers

Abstract

We report a novel splicing-based pressure-assisted melt-filling technique for creating metallic nanowires in hollow channels in microstructured silica fibers. Wires with diameters as small as 120 nm (typical aspect ration 50:1) could be realized at a filling pressure of 300 bar. As an example we investigate a conventional single-mode step-index fiber with a parallel gold nanowire (wire diameter 510 nm) running next to the core. Optical transmission spectra show dips at wavelengths where guided surface plasmon modes on the nanowire phase match to the glass core mode. By monitoring the side-scattered light at narrow breaks in the nanowire, the loss could be estimated. Values as low as 0.7 dB/mm were measured at resonance, corresponding to those of an ultra-long-range eigenmode of the glass-core/nanowire system. By thermal treatment the hollow channel could be collapsed controllably, permitting creation of a conical gold nanowire, the optical properties of which could be monitored by side-scattering. The reproducibility of the technique and the high optical quality of the wires suggest applications in fields such as nonlinear plasmonics, near-field scanning optical microscope tips, cylindrical polarizers, optical sensing and telecommunications.

Circular hole ENZ photonic crystal fibers exhibit high birefringence

“…Practical implementations of ENZ materials into structured fibers can be accomplished with techniques introduced to realize optical fibers with more complex material compositions [31,32] and hybrid optical fibers [33,34]. One could simply insert naturally occurring bulk materials having ENZ properties directly into a structured fiber using direct thermal drawing [35], pressure-assisted melt filling techniques [36], or chemical depositions [37][38][39]. Our reported PCF designs could be achieved using the pressure-assisted melt filling technique to insert the bulk-form of KCl [26] or semi-conductor plasmonic materials [40] into the appropriate holes in the host silicon material for the THz PCF.…”

Hybrid Optical Fibers – An Innovative Platform for In‐Fiber Photonic Devices

“…One recently developed post-processing platform is pressure-assisted melt fi lling (PAMF). [ 46 ] Here, the material to-be-fi lled is liquefi ed via melting and pressed into the holes of the fi ber matrix, which can be a MOF or just a capillary. In contrast to thermal drawing, this technique is comparably insensitive to a mismatch of thermal expansion coeffi cients or other highlighted requirements, and thus enables the introduction of a large variety of materials into fi bers.…”

“…[ 47,48 ] The last two constrains are most relaxed if silica fi bers are used as hosts, allowing the use of materials with melting temperatures up to 1400 °C (viscosity of silica is 10 9 Pa s at that temperature). [ 49 ] Various experimental confi guration of this technique have been implemented, [ 46,50 ] whereas the splice-fi lling setup represents the optimal compromise with respect to all experimental constrains ( Figure 3 a). This particular arrangement is straightforward to use, since it relies only on state-of-the-art splicing equipment and a simple furnace, which are available in almost any optics laboratory.…”

“…Adapted with permission. [ 46 ] Copyright 2011, OSA. e) Germanium nanowire selectively fi lled into a hole in the fi rst ring of a photonic crystal fi ber.…”

Plasmonic Nanowire Continuum Light Source

“…Furthermore, gold nanowires have recently been integrated into optical fibers by pumping molten metal into the hollow channels of solid-core photonic crystal fibers (PCFs) [3,4], as well as through "stack and draw" techniques to achieve arrays of nanowires in glass matrices. Apart from extremely large aspect ratios these wires are free of impurities and the glass matrix also serves as a mechanical host to hold the nanowires in place.…”