Robust plasmonic tips fabricated by the tapering of composite hybrid silicate microfibers with metallic core

Abstract

The development of plasmonic devices for sensing applications can offer high sensitivity and a dramatic improvement to the detection limits due to the high field enhancement at the metal surfaces. The platform proposed here is a tapered hybrid microfiber comprising a metal core and a glass cladding. The existence of a glass cladding not only serves as a mechanical host for the metal core, but also provides ease of handling regarding the tapering process. The advantages of this composite material system over pure metal tips are the absence of impurities and the multiple excitation of the plasmon modes due to the total internal reflection at the glass/air interface. The improved field enhancement at the apex of these tapered microwires was calculated through Finite Element Method (FEM) simulations. Enhancement factors up to 10 4 were theoretically observed for this type of tapered microwires. The use of different metals having different melting points and thermal expansion coefficients as well as different glass thicknesses can lead to an optimization of the tapering process conditions in order to achieve tapered microwires with the desirable geometrical characteristics.

All-Fiber Plasmonic Platform Based on Hybrid Composite Metal/Glass Microwires

“…[19][20][21] Metal tips [22][23][24][25] are very promising nanofocusing structures since they enable the confinement of light at the tip apex providing strong field localization. In this work microwires composed of noble metal cores with glass cladding 26 are proposed and employed for the development of plasmonic metal tips. The glass cladding not only mechanically supports and shields the metal core, but also due to the total internal reflections at the glass/air interface the plasmon modes travelling along the metal/dielectric interface are continuously re-excited.…”

Microspheres Formation in a Glass–Metal Hybrid Fiber System: Application in Optical Microwires

“…Although the drawing of fibers containing base metals has already been investigated [5], the study of fibers containing noble metals is of intense interest for plasmonic devices. The manufacturing and post processing [6,7] of such fibers though is quite challenging due to the combination of materials with different mechanical and physicochemical properties. At high temperature processing conditions, a number of instabilities induce various microfluidic phenomena leading in turn to formation of various embedded microstructures.…”

Theoretical study and development of photonic devices and sensors

“…Optical fibers comprise a platform that could be adapted for the development of plasmonic devices [52], [53], combining also the ease of light coupling and thus allowing better operational characteristics. Such an optical fiber platform implemented in a tapered optical fiber with a thin metallic cladding is studied in this chapter.…”

“…Although the drawing of fibers containing base metals has already been investigated [62], the study of fibers containing noble metals is of intense interest for plasmonic devices. The manufacturing and post processing [53], [63] of such fibers though is quite challenging due to the combination of materials with different mechanical and physicochemical properties. At high temperature processing conditions, a number of instabilities induce various microfluidic phenomena leading in turn to formation of various embedded microstructures.…”

“…Photonic biosensors are widely used since they offer various advantages such as immunity to electromagnetic interference, reliability, fast response, large dynamic range and ability to operate in harsh environmental conditions. Various photonic structures have been proposed for biological sensing including optofluidics [86], PR biosensors [53], [87]- [89], photonic crystals [90], fluorescence sensors [91] and photonic resonant optical microcavities [32], [92], [93].…”