Fig. 1. Schematic diagram of micro taper side-polished fiber MZI

Fig. 2. Simulation results of the micro taper side-polished fiber MZI structure. (a) Interference spectra under different refractive indexes; (b) linear fit curve diagram of refractive index sensing; (c) light field transmission diagram at wavelength of 1564 nm (dip A); (d) light field transmission diagram at wavelength of 1558 nm (peak B)

Fig. 3. Micrograph of micro taper welding point

Fig. 4. Fiber side-polished system and the micrograph of side-polished area. (a) Fiber side-polished system; (b) micrograph of fiber side-polished area

Fig. 5. Experimental device for refractive index and temperature measurement

Fig. 6. Sensing curves of micro taper MZI structures under different refractive indexes. (a)--(c) Refractive index response spectra of micro taper MZI structures with side-polished depths of 0, 29.2, and 41.7 μm; (d)--(f) linear fit of sensing curve

Fig. 7. Sensing curves of micro taper MZI structures under different temperatures. (a)--(c) Temperature response spectra of micro taper MZI structures with side-polished depths of 0, 29.2, and 41.7 μm; (d)--(f) linear fit of sensing curve

Fig. 8. Humidity sensing mechanism and microscope image of GO. (a) Humidity sensing mechanism; (b) cross section of fiber coated with GO film; (c) nanolayer thickness after deposition with GO concentration of 2 mg/mL

Fig. 9. Experimental device for humidity measurement

Fig. 10. Temperature and humidity sensing curves. (a) (b) Spectrum responses of dip1 and dip2 with humidity and temperature, respectively; (c) (d) linear fits of humidity and temperature sensing curve