Fig. 1. Schematic diagram of current sensor based on microcapillary resonator

Fig. 2. Preparation process of microcapillary resonator. (a) Schematic of preparation process; (b) optical micrograph of microcapillary resonator

Fig. 3. Simulation result of microcapillary resonator coupled by micro-nano fiber waveguide. (a) Electric field distribution; (b) simulated transmission spectrum

Fig. 4. Experimental schematic diagram based on microcapillary resonator current sensor

Fig. 5. Resonance spectrum of microcapillary resonator. (a) Transmission spectrum, where inset shows Lorentz fit curve of q=0; (b) theoretical analysis result; (c) corresponding electric distributions of the first five axial modes

Fig. 6. Current response characteristics of hollow microcapillary resonator. (a) Transmittance curves under different currents; (b) resonant wavelength shift as function of current

Fig. 7. Current response characteristics of microcapillary resonator with 50% nanoparticles. (a) Transmittance curves under different currents; (b) resonant wavelength shift as function of current

Fig. 8. Current response characteristics of microcapillary resonator with 100% nanoparticles. (a) Transmittance curves under different currents; (b) resonant wavelength shift as function of current

Fig. 9. Comparison of relationship between resonant wavelength shift and current among hollow microcapillary resonator, microcapillary resonator with 50% nanoparticles, and microcapillary resonator with 100% nanoparticles