Fig. 1. Structure and schematic of FP interferometer

Fig. 2. Fabrication process of FP sensing interferometer

Fig. 3. Effects of length change of reference cavity on spectrum. (a) Increasing cavity length; (b) reducing cavity length

Fig. 4. Effects of length change of sensing cavity on spectrum. (a) Increasing cavity length; (b) reducing cavity length

Fig. 5. Experimental device diagram of virtual parallel vernier temperature sensor

Fig. 6. Spatial spectrum of sensing interferometer at 51 ℃ with interference spectrum of sensing interferometer at 51 ℃ shown in inset

Fig. 7. Experimental results of temperature measurement for sensing interferometer. (a) Spectra in range of 51-55 ℃; (b) fitting result at valley point 1

Fig. 8. Repeated measurement result of target valley point at 51 ℃

Fig. 9. Experimental results of temperature measurement for virtual reference interferometer when LVR=180μm. (a) Spectra in range of 51-55 ℃; (b) fitting result at valley point A of envelope spectrum

Fig. 10. Experimental results of temperature measurement for virtual reference interferometer when LVR=160μm. (a) Spectra in range of 51-55 ℃; (b) fitting result at valley point B of envelope spectrum

Fig. 11. Experimental results of temperature measurement for virtual reference interferometer when LVR=150μm. (a) Spectra in range of 51-55 ℃; (b) fitting result at valley point C of envelope spectrum

Fig. 12. Experimental results of temperature measurement for virtual reference interferometer when LVR=144μm. (a) Spectra in range of 51-55 ℃; (b) fitting result at valley point D of envelope spectrum

Fig. 13. Experimental results of temperature measurement for virtual reference interferometer when LVR=140μm. (a) Spectra in range of 51-55 ℃; (b) fitting result at valley point E of envelope spectrum