Intensity modulated SMF cascaded tapers with a hollow core PCF based microcavity for curvature sensing

We propose a highly sensitive curvature sensor based on cascaded single mode fiber (SMF) tapers with a microcavity. The microcavity is created by splicing a small piece of hollow core photonic crystal fiber (HCPCF) at the end of an SMF to obtain a sharp interference pattern. Experimental results show that two SMF tapers enhance the curvature sensitivity of the system and by changing the tapering parameters of the second taper, the curvature sensitivity of the system can be tailored, together with the fringe contrast of the interference pattern. A maximum curvature sensitivity of 10.4 dB/m(-1) is observed in the curvature range 0 to 1 m(-1) for a second taper diameter of 18 mu m. The sensing setup is highly stable and shows very low temperature sensitivity. As the interrogation is intensity based, a low cost optical power meter can be utilized to determine the curvature.