Fig. 1. (a) Profile image of the SHF. (b) Schematic diagram of the dual-channel sensor based on dual LPFGs. (c) Side view of LPG-A. (d) Side view of LPG-B. (e) Top view of LPG-A. (f) Top view of LPG-B.

Fig. 2. Schematic diagram of the experimental setup for dual-LPG sensor fabrication.

Fig. 3. Transmission spectra for LPG-A (black line) and dual LPGs (LPG-A and LPG-B, red line) in air.

Fig. 4. Schematic diagram of the experimental setup.

Fig. 5. (a) The transmission spectrum of LPG-A when we load the liquid samples in Channel-A. (b) The transmission spectrum of LPG-B when we load the liquid samples in Channel-A. (c) The transmission spectrum of LPG-A when we load the liquid samples in Channel-B. (d) The transmission spectrum of LPG-B when we load the liquid samples in Channel-B. (e) RI sensitivity of LPG-A and LPG-B when we load the liquid sample in Channel-A. (f) RI sensitivity of LPG-A and LPG-B when we load the liquid sample in Channel-B.

Fig. 6. Sensor output as determined by Eq. (5) for variation of RI in one channel at a constant RI in the other channel.