Abstract
Micro/nanofibres (MNFs) are optical fibres with diameters close to or below the vacuum wavelength of visible or near-infrared light. Due to its wavelength- or sub-wavelength scale diameter and relatively large index contrast between the core and cladding, an MNF can offer engineerable waveguiding properties including optical confinement, fractional evanescent fields and surface intensity, which is very attractive to optical sensing on the micro and nanometer scale. In particular, the waveguided low-loss tightly confined large fractional evanescent fields, enabled by atomic level surface roughness and extraordinary geometric and material uniformity in a glass MNF, is one of its most prominent merits in realizing optical sensing with high sensitivity and great versatility. Meanwhile, the mesoporous matrix and small diameter of a polymer MNF, make it an excellent host fibre for functional materials for fast-response optical sensing. In this tutorial, we first introduce the basics of MNF optics and MNF optical sensors, and review the progress and current status of this field. Then, we discuss challenges and prospects of MNF sensors to some extent, with several clues for future studies. Finally, we conclude with a brief outlook for MNF optical sensors.
Highlights
The “ability” of using light to sense environmental changes or exotic objectives has been developed over more than a hundred million years during the evolution of creatures on this planet [1], while the “technique” of optical sensing was emerged only a few hundreds of years ago [2]
(a) Optical micrograph of a 1.2-μm-diameter MNF tapered from a standard glass fibre. (b) In-situ (a) Optical micrograph of a 1.2-μm-diameter MNF tapered from a standard glass fibre; (b) In-situ transmittance measured during the tapering process at 1550 nm wavelength. (c) Transmission spectra transmittance measured during the tapering process at 1550 nm wavelength; (c) Transmission spectra of MNFs with different diameters
MNF operated at 1.55-μm wavelength) [77], they realized broadband (400~1700 nm) single-mode operation of a 2 × 2 fused MNF coupler [Figure 15a], which effectively suppressed higher-order modes presented at the input fibre and provided efficient power splitting into the fundamental mode at the two output ports [Figure 15b], showing the possibility for optical sensing based on the coupling-efficiency-dependent response
Summary
The “ability” of using light to sense environmental changes or exotic objectives has been developed over more than a hundred million years during the evolution of creatures on this planet [1], while the “technique” of optical sensing was emerged only a few hundreds of years ago [2]. Based on the taper-drawing process mentioned above, in recent years, a number 4ofof 27 improvements on this technique have been reported for fabricating MNFs with various parameters including ultra-small diameters [29], reduced propagation losses [30,31,32], optimized tapering profiles and controllable cross-section geometries [33,34]. For polymer MNFs, a number of fabrication techniques have been successfully developed [24], among which physical drawing is the best approach to optical-quality MNFs with excellent geometric uniformity and surface smoothness. MNFs, a number of propagation fabrication techniques have been successfully developed ultra-small diameters [29], reduced losses [30,31,32], optimized tapering profiles [24], and among whichcross-section physical drawing is the best approach to optical-quality with excellent geometric controllable geometries [33,34]. Millimeters to meters per second, depending on the material and temperature) and the solution concentration, the diameter of the MNF can be roughly determined [36,37]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
