Fig. 1. Examples of optical-fiber and integrated SPR devices. (a) Uniform periodic structure on single-mode optical fiber's end-facet[13]; (b) device on multi-mode optical fiber's end-facet[14]; (c) device on optical fiber's sidewall[29]; (d) SPR microcavity on single-mode optical fiber's end-facet[25]

Fig. 2. SPR microcavities on single-mode optical fiber end-facets. (a)(b) Schematic of a structure for achieving an intraband SPP cavity mode and its SEM image near the center of the structure[25]; (c)(d) schematic of a structure for achieving a defect cavity mode in the SPP bandgap and its SEM image near the center of the structure[25]

Fig. 3. Theoretical and experimental results for SPR microcavity resonant state. (a) SPP band diagram for infinitely wide nanoslit array with period of 645 nm[44]; (b) defect modes (arrows) in the SPP bandgap (dash-dot lines), and their dependence on the defect's width s, refer to Fig. 2(c) for the definition of s[44]; (c) reflection spectra of an intraband SPP cavity mode structure on single-mode optical fiber's end-facet[25]

Fig. 4. Three transfer techniques for fabricating SPR structures on optical fiber end-facets. (a) Nanoskiving[12]; (b) decal transfer[10]; (c) glue-and-strip[25]

Fig. 5. Biomolecule interaction analysis experiment based on SPR microcavity sensor on single-mode optical fiber's end-facet[7]. Except for the first step which is baseline, each step comprises of two parts which are immersing the sensor in the molecule solution and then in the buffer solution. There is a little spike on the testing curve between the two parts

Fig. 6. Schematics of typical acousto-optic micro devices (in both devices, optical waveguiding and acousto-optic transduction are performed by the same material). (a) Micro-ring[54]; (b) Fabry-Pérot cavity[62]

Fig. 7. Ultrasound detection with an SPR microcavity on a single-mode optical fiber end-facet. (a) Schematic of the experimental system; (b) SPR reflection spectrum; (c) undulation of laser power reflection in response to a series of ultrasound pulse with a central frequency of 10 MHz

Fig. 8. Focusing radially polarized laser beam to excite structure which contains a 60-nm gold nanosphere, a monolayer of molecules, and an atomically flat gold surface[76]. (a) Schematic, with the gold nanosphere's mirror image; (b) simulation result for the vertical electric field component's intensity distribution in the hotspot under vertical LSPR resonance, with color scale indicating enhancement compared to the incident light; (c) experimental Raman spectra of 20 different gold nanospheres, each c

Fig. 9. Dynamically tuned plasmonic antennas. (a) The LSPR of a silver nanowire-mirror structure is tuned by thermal expansion of molecules in the gap[117]; (b) the relative position of a single fluorescence molecule in a plasmonic hotspot is controlled by DNA origami[119]; (c) the spatial polarization state of a laser focal spot is imaged by scanning a gold nanosphere on aerogel, with an imaging result in the inset; (d) tuning and measurement of single and few molecules using an LSPR probe on STM (top

Fig. 10. Plasmonic structures integrated on SPM probes. (a) An LSPR antenna on an AFM probe apex has been fabricated using focused ion beam milling[128]; (b) a pair of gold spheres on AFM probe apexes comprise a dimer LSPR antenna, with its gap size controlled and measured by conductive AFM[96]; (c) a metallic grating carved on an AFM probe couples incident light waves to SPPs, and focuses SPPs to the probe apex[133]; (d) a helical gold grating carved on an AFM probe is used to detect enantioselective op

Fig. 11. AFM technology based on gold nanoparticle probes on tapered optical fibers' apexes. (a) As a gold nanoparticle probe approaches another gold nanoparticle, the four-wave-mixing signal increases significantly[146]; (b) as a gold nanoparticle probe approaches a single molecule, the molecular fluorescence experiences the process from enhancement to quenching[147]

Fig. 12. Scanning LSPR microscopy of a 100 nm gold nanosphere on a glass substrate, using a 100 nm gold nanosphere on a tapered optical fiber's apex as the AFM probe, and its LSPR scattering spectrum as the imaged quantity[150]. (a) Schematic showing that as the gold nanosphere probe approaches a gold nanosphere target, a vertical dimer mode appears in the LSPR scattering spectrum; (b) line scanning result for morphology (top) and LSPR (bottom)