Fig. 1. The mode field transmission and power distribution within different ORCPs. (a) Schematic diagram of ORCP; (b)(e) mode field transmission in ORCP without bent and with bent; (c)(f) power propagation in the core and cladding of ORCP without bent and with bent; (d)(g) enlarged view of power propagation details in the cladding within the coupling zone of the ORCP without bent and with bent

Fig. 2. Simulated reflection spectra of ORCP with different structural parameters. (a) Different ERIDs with a fixed L; (b) different L with a fixed ERID

Fig. 3. Microscopic images and the measured spectral results of the ORCP. (a) At the coupling region; (b) at the fiber cross-section; (c) the output spectrum

Fig. 4. Curvature sensing experiment of the ORCP. (a) Experimental setup; (b) principle analysis

Fig. 5. Curvature sensing experiment of the absolute symmetric ORCP. (a) Schematic diagram of the absolute symmetric ORCP; (b) experimental setup

Fig. 6. Experimental results of curvature sensing based on absolute symmetric ORCP. (a) The transmission spectra with different curvatures; (b) fitting relationship between wavelength, transmission and curvature

Fig. 7. Experimental results of curvature sensing based on ORCP structure. (a) The reflection spectra and the envelopes with different curvatures; (b) fitting relationship between wavelength, reflection and curvature

Fig. 8. Experimental setup of ORCP-FVS

Fig. 9. The measured response of the ORCP-FVS with different single-frequency vibration signals. (a)(c) The measured frequency-domain spectra from 11 kHz to 400 kHz; (b) (d) (e) the corresponding time-domain spectra of vibration signals and SNRs from 11 kHz to 20 MHz; (f) the linearity of the ORCP-FVS for vibration detection of the n-randomly applied signal frequencies from 185 Hz to 20 MHz, the inset is the frequency-domain spectra from 185 Hz to 900 Hz

Fig. 10. The measured relationship between frequency of applied vibration signal and SNR

Fig. 11. Measured vibration signals with different amplitudes. (a) The time-domain spectra ; (b) measured vibration amplitudes versus driving voltage amplitudes

Fig. 12. Measured damped vibration response of the ORCP-FVS. (a) Time-domain spectra; (b) frequency-domain spectra

Fig. 13. The measured speech recognition results of ORCP-FCS. (a) The measured time-domain spectra with different sounds; (b) the corresponding frequency-domain spectra

Fig. 14. The measured stability of the ORCP. (a) The measured reflection spectra with different temperature; (b) the corresponding relationship between temperature and wavelength; (c) the measured reflection spectra within 1 h; (d) the wavelength fluctuation within 1 h