Fig. 1. (a) Schematic configuration and principle of the proposed sensor. (b) Microscopic image of the bitaper. (c) Microscopic image of the core-offset joint.

Fig. 2. Schematic diagram of the experimental system.

Fig. 3. (a) Transmission spectrum of the sensor and (b) its spatial frequency spectrum obtained by taking the Fourier transform.

Fig. 4. Measured spectra with (a) RI variations and (b) temperature variations.

Fig. 5. (a) Spatial frequency spectra calculated from Fig. 4(a). (b) Spatial frequency spectra calculated from Fig. 4(b). The insets are the enlarged displays.

Fig. 6. Wavelength spectra obtained by taking the IFFT of the selected frequency components in Fig. 4(a) as the RI changes: (a) DMI patterns correspond to core-cladding 1, and (b) DMI patterns correspond to core-cladding 2.

Fig. 7. Wavelength spectra obtained by taking the IFFT of the selected frequency components in Fig. 4(b) as the applied temperature changes: (a) DMI patterns correspond to core-cladding 1, and (b) DMI patterns correspond to core-cladding 2.

Fig. 8. Dependences of the wavelength shift on the RI and temperature for the core-cladding 1 and core-cladding 2 interference patterns.