• Chinese Optics Letters
  • Vol. 19, Issue 10, 102202 (2021)
Chao Liu1、*, Jingwei Lü1, Wei Liu1, Famei Wang1, and Paul K. Chu2
Author Affiliations
  • 1School of Physics and Electronic Engineering, Northeast Petroleum University, Daqing 163318, China
  • 2Department of Physics, Department of Materials Science & Engineering, and Department of Biomedical Engineering, City University of Hong Kong, Hong Kong, China
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    SPR excitation by prism coupling using the Kretschmann configuration.
    Fig. 1. SPR excitation by prism coupling using the Kretschmann configuration.
    Dispersion relation of TM incident light coupling with SPP.
    Fig. 2. Dispersion relation of TM incident light coupling with SPP.
    Methodology of SPR measurement: (a) SPR spectra for different RIs and (b) relationship between the wavelength and RI.
    Fig. 3. Methodology of SPR measurement: (a) SPR spectra for different RIs and (b) relationship between the wavelength and RI.
    (a) Loss spectra of two PCFs with and without defect. (b) Electronic field distributions of the PCF with defect: insets (c) and (d) show the electronic field distributions of the fundamental core-guided mode and higher-order plasmonic mode at λ = 575 nm; insets (e) and (f) show the energy distribution of the fundamental core-guided mode and fundamental plasmonic mode at λ = 632 nm[57].
    Fig. 4. (a) Loss spectra of two PCFs with and without defect. (b) Electronic field distributions of the PCF with defect: insets (c) and (d) show the electronic field distributions of the fundamental core-guided mode and higher-order plasmonic mode at λ = 575 nm; insets (e) and (f) show the energy distribution of the fundamental core-guided mode and fundamental plasmonic mode at λ = 632 nm[57].
    Electronic field distributions of the sensor for different modes: (a) for the core-guided mode, (b) for the plasmonic mode, and (c) for the two modes at resonance point[63].
    Fig. 5. Electronic field distributions of the sensor for different modes: (a) for the core-guided mode, (b) for the plasmonic mode, and (c) for the two modes at resonance point[63].
    (a) Schematic illustration of the side-polished sensor. (b) Dispersion relations and loss spectra of the sensor. (c) Resonant curves for RIs of 1.00–1.20. (d) Resonant curves for RIs of 1.21–1.37[64].
    Fig. 6. (a) Schematic illustration of the side-polished sensor. (b) Dispersion relations and loss spectra of the sensor. (c) Resonant curves for RIs of 1.00–1.20. (d) Resonant curves for RIs of 1.21–1.37[64].
    (a) 2D diagram of the sensor. (b) Three-dimensional (3D) diagram of the sensor. (c) Dispersion relations and loss spectrum of the sensor (red line represents channel 1 for na = 1.35, green line represents channel 2 for na = 1.38). (d) Electric field distributions of the sensor for different wavelengths[68].
    Fig. 7. (a) 2D diagram of the sensor. (b) Three-dimensional (3D) diagram of the sensor. (c) Dispersion relations and loss spectrum of the sensor (red line represents channel 1 for na = 1.35, green line represents channel 2 for na = 1.38). (d) Electric field distributions of the sensor for different wavelengths[68].
    Schematics of the 2D cross section: (a) coated with an Au layer, (b) coated with Au and titanium dioxide layers (TiO2), and (c) coated with the Au-TiO2 grating[74].
    Fig. 8. Schematics of the 2D cross section: (a) coated with an Au layer, (b) coated with Au and titanium dioxide layers (TiO2), and (c) coated with the Au-TiO2 grating[74].
    Typical cross-sectional views of various PCF-SPR sensors. (a) Graphene over ITO coated PQF[80]; (b) a Ag core[81]; (c) hexagonal structure consisting of two air hole rings with a central air hole[82]; (d) eccentric core PQF with ITO coating[83]; (e) twin-core PCF with Au coating[84]; (f) analyte filling with Au-Ta2O5 coating[87]; (g) two open-ring channels with Au coating[63]; (h) two parallel D-shaped structures[58].
    Fig. 9. Typical cross-sectional views of various PCF-SPR sensors. (a) Graphene over ITO coated PQF[80]; (b) a Ag core[81]; (c) hexagonal structure consisting of two air hole rings with a central air hole[82]; (d) eccentric core PQF with ITO coating[83]; (e) twin-core PCF with Au coating[84]; (f) analyte filling with Au-Ta2O5 coating[87]; (g) two open-ring channels with Au coating[63]; (h) two parallel D-shaped structures[58].
    (a) General setup for practical sensing; (b) amplitude sensitivity curves of the moisture-monitoring sensor for the x-polarized mode; (c) amplitude sensitivity curves of the moisture-monitoring sensor for the y-polarized mode (d = 0.76 µm, n = 1.330–1.340, dc = 0.3 µm, tg = 40.12 nm, and Λ = 0.8 µm)[114].
    Fig. 10. (a) General setup for practical sensing; (b) amplitude sensitivity curves of the moisture-monitoring sensor for the x-polarized mode; (c) amplitude sensitivity curves of the moisture-monitoring sensor for the y-polarized mode (d = 0.76 µm, n = 1.330–1.340, dc = 0.3 µm, tg = 40.12 nm, and Λ = 0.8 µm)[114].
    Illustration of the stack-and-draw method for PCF fabrication[125].
    Fig. 11. Illustration of the stack-and-draw method for PCF fabrication[125].
    (a) Schematic illustration of HPCVD. (b) Si tubes in a PCF (scale bar: 1 mm). (c) Image of Au nanoparticles array within a 1.6 µm capillary. (d) Image of Au film grown on the inner wall of the Si tube inside PCF (scale bar: 2 µm)[126].
    Fig. 12. (a) Schematic illustration of HPCVD. (b) Si tubes in a PCF (scale bar: 1 mm). (c) Image of Au nanoparticles array within a 1.6 µm capillary. (d) Image of Au film grown on the inner wall of the Si tube inside PCF (scale bar: 2 µm)[126].
    (a) Schematic of suspended-core fiber front view with Au nanoparticles coating. (b) and (c) SEM images of the inner walls of the suspended-core fiber coated with Au nanoparticles (30 nm diameter spheres): (b) an overview and (c) a zoomed image[127].
    Fig. 13. (a) Schematic of suspended-core fiber front view with Au nanoparticles coating. (b) and (c) SEM images of the inner walls of the suspended-core fiber coated with Au nanoparticles (30 nm diameter spheres): (b) an overview and (c) a zoomed image[127].
    (a) Structure of the SPR sensor and (b) microscopic image of the cross section of the fabricated suspended-core fiber[131].
    Fig. 14. (a) Structure of the SPR sensor and (b) microscopic image of the cross section of the fabricated suspended-core fiber[131].
    SEM images of the cross section of the sputtered fibers[131]: (a) for ∼54 nm Ag film, (b) for ∼66 nm Ag film, and (c) for ∼83 nm Ag film[131].
    Fig. 15. SEM images of the cross section of the sputtered fibers[131]: (a) for ∼54 nm Ag film, (b) for ∼66 nm Ag film, and (c) for ∼83 nm Ag film[131].
    (a) Schematic of the plasmonic nanoparticle-functionalized suspended-core fiber and (b) SEM image of the microstructured section of the fiber[132].
    Fig. 16. (a) Schematic of the plasmonic nanoparticle-functionalized suspended-core fiber and (b)  SEM image of the microstructured section of the fiber[132].
    (a) Spliced-fiber pressure-filling technique and (b) optical side views of the splices (left-hand column) and SEM images of the cleaved end-faces (right-hand column); (c) solid-core PCF with all its channels filled with Au, (d) PCF in which only two channels are filled with Au, (e) modified step index fiber with a parallel Au nanowire[134].
    Fig. 17. (a) Spliced-fiber pressure-filling technique and (b) optical side views of the splices (left-hand column) and SEM images of the cleaved end-faces (right-hand column); (c) solid-core PCF with all its channels filled with Au, (d) PCF in which only two channels are filled with Au, (e) modified step index fiber with a parallel Au nanowire[134].
    (a) D-shaped model. (b) SEM image of the PCF before polishing. (c) Cross section of the Au-coated D-shaped PCF. (d) Side-polished surface of the D-shaped PCF with a Au coating. (e) Schematic diagram of the real-time online measurement system[121].
    Fig. 18. (a) D-shaped model. (b) SEM image of the PCF before polishing. (c) Cross section of the Au-coated D-shaped PCF. (d) Side-polished surface of the D-shaped PCF with a Au coating. (e) Schematic diagram of the real-time online measurement system[121].
    (a) Structure of the sensor. (b) Schematic diagram of the simulated model. (c) Transmitted light microscopic image. (d) Reflected light microscopic image[143].
    Fig. 19. (a) Structure of the sensor. (b) Schematic diagram of the simulated model. (c) Transmitted light microscopic image. (d) Reflected light microscopic image[143].
    (a) End face microscope diagram of PCF. (b) Fusing splice image of MMF-PCF. (c) Schematic diagrams of surface functionalization and immune-sensing process. (d) SEM of Au film on the fiber. (e) Optical properties of the sensor in the immobilization and human IgG[145].
    Fig. 20. (a) End face microscope diagram of PCF. (b) Fusing splice image of MMF-PCF. (c) Schematic diagrams of surface functionalization and immune-sensing process. (d) SEM of Au film on the fiber. (e) Optical properties of the sensor in the immobilization and human IgG[145].
    Ref.CharacteristicRefractive Index RangeMax. Sensitivity (nm/RIU)Resolution (RIU)Str. Diagram
    [88]Birefringence PCF1.00–1.436300
    [76]D-shaped PCF1.18–1.3620,000
    [90]Concave-shaped PCF1.19–1.2910,700
    [60]D-shaped PCF1.20–1.2911,055
    [66]Microchannel PCF1.22–1.3751,000
    [62]Gold-nanowire-coated PCF1.27–1.366000
    [77]D-shaped PCF1.27–1.3210,493
    [91]Gold-coated PCF1.29–1.494156
    [92]PCF with circular air holes1.32–1.4330,500 (x), 41,500 (y) (x), (y)
    [40]PCF with exposed core1.33–1.4213,500
    [78]Graphene-based D-shaped PCF1.33–1.373700
    [93]Copper-graphene-based PCF1.33–1.372000
    [94]External gold-layer-coated PCF1.33–1.374000
    [95]Hexagonal sensor1.33–1.4211,000
    [96]PCF with exposed core1.33–1.4216,400
    [97]Au-coated dual-core PCF1.33–1.516021
    [98]Hollow core Ag-coated PCF1.36–1.374200
    [79]D-shaped PCF coated with gratings1.36–1.383340Not applicable
    [99]Eight-fold eccentric core PQF1.38–1.41396,667
    [100]Flattened PCF1.49–1.544782
    [75]Four large channels1.63–1.793233
    Table 1. Refractive Index Ranges of Recently Reported Sensors
    Ref.CharacteristicWavelength Range (nm)Max. Sensitivity (nm/RIU)Resolution (RIU)Str. Diagram
    [40]PCF with exposed core460–62013,500/
    [78]Graphene-coated D-shaped PCF480–6503700
    [101]Hollow core PCF with silver nanowires560–61014,240/
    [50]Hollow core D-shaped PCF550–7502900/
    [86]Multichannel PCF550–9504600
    [72]D-shaped PCF550–177046,000
    [102]Dual-core PCF600–120028,000
    [103]Square array PCF630–11807250
    [104]Bilaterally gold-coated PCF1000–340030,000
    [41]ITO-coated D-shaped PCF1200–225015,000
    [83]PCF with eccentric core1400–220021,000
    [105]ITO-coated D-shaped PCF1870–230017,000
    [60]D-shaped PCF with open ring2300–285011,055
    Table 2. Comparison of the Wavelength Ranges of Recently Reported Sensors
    Ref.Fiber TypeRefractive Index RangeWavelength Range (nm)Max. Sensitivity (nm/RIU)Resolution (RIU)Amp. Sensitivity (RIU−1)Str. Diagram
    [117]Dual-channel PCF1.33–1.40500–100011,600N/A
    [113]PCF with air core1.33–1.41800–170011,700159.70
    [89]Dual D-shaped PCF1.36–1.41640–104014,6001222
    [118]Multi-analyte PCF1.34–1.41560–99018,000427
    [119]D-shaped PCF1.35–1.381200–240018,900/
    [120]Gold-coated PCF1.33–1.40550–120019,000985
    [121]D-shaped PCF1.33–13.4500–90021,700/
    [122]-Au-coated PCF1.32–1.40600–108023,000/
    [111]H-shaped PCF1.33–1.49800–200025,900N/A
    [123]D-shaped PCF1.33–1.43600–110031,600550
    [112]D-shaped PQF1.415–1.4271400–170034,000N/A
    [115]Gold-coated PCF1.33–1.401520–167048,269N/A
    [116]D-shaped PCF1.32–1.40410–179048,900738.74
    [124]Dual-core PCF1.29–1.391200–3500116,0002320
    Table 3. Comparison of the Characteristics of Selected High Sensitivity of PCF-SPR Sensors Reported Recently
    Ref.Fiber TypeSensing RegionDetection RangeSensitivity
    [145]MMF-PCFProtein A/Au NPs/Au film1–15 µg/mL3915 nm/RIU
    [146]MMF-PCF-MMFAu/PDMS film1.33–1.39 RIU4613.73 nm/RIU
    [147]SMF-MMF-PCFCollapsed regionµε0–5000−2.21 pm/µε
    [148]GO-coated PCFCollapsed regionsµε0–10003.1 pm/µε
    [149]Ferrofluid-coated PCFFiber taper100–600 Gs16.04 pm/µε
    [150]V-shaped PCFAu film1.333–1.385 RIU3376 nm/RIU
    [151]Exposed-core PCFAg film1.33–1.37 RIU1800 nm/RIU
    [152]D-shaped PCFAu film1.40–1.42 RIU7381 nm/RIU
    [153]D-shaped PCFAu film1.3388–1.3638 RIU2336.2 nm/RIU
    [154]Hollow-core PCFAg nanoparticlesNot applicable1010mol/L
    [155]Suspended-core PCFAg core/gold shellNot applicable107105mol/L
    [156]Hollow core PCFAu nanoparticlesNot applicable200 µg/mL
    [157]D-shaped MMFAu film1.343–1.373 RIU3513.3 nm/RIU
    [158]Hollow core PCFAg nanoparticlesNot applicable300 cells/mL
    Table 4. Comparisons of Plasmonic PCF Sensors
    Copy Citation Text
    Chao Liu, Jingwei Lü, Wei Liu, Famei Wang, Paul K. Chu. Overview of refractive index sensors comprising photonic crystal fibers based on the surface plasmon resonance effect [Invited][J]. Chinese Optics Letters, 2021, 19(10): 102202
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    Category: Optical Design and Fabrication
    Received: Jan. 21, 2021
    Accepted: Mar. 17, 2021
    Published Online: Sep. 2, 2021
    The Author Email: Chao Liu (msm-liu@126.com)