Highly sensitive RI and temperature sensor based on cascaded LPGs at near the phase-matching turning point

We demonstrated a highly sensitivity refractive index (RI) and temperature sensor based on cascaded long-period gratings (LPGs) operating at near the phase-matching turning point (PMTP). A series of narrow resonance peaks formed by interference between cladding mode and core mode showed relative high Q-factor comparison with the one of the LPG. The experimental results showed that such fiber sensor have RI sensitivity of 1360nm/RIU@1.33 and 3669.7nm/RIU@1.41 and the temperature sensitivity of 4.079 nm/°C.