A high sensitivity strain sensor based on a long-period fiber grating with curvilinear core in taper structure

In this article, a highly sensitive strain sensor based on a long-period fiber grating (LPFG) with curvilinear core in taper structure (CT-LPFG) is described. The proposed LPFG has been fabricated by periodically cutting and electro-discharge along the axis of single-mode fiber (SMF). It consists of curvilinear core taper structures, all of which exhibit asymmetry along the axis. This fabrication method converts SMF into the optical fiber with special cores. The unique design of the curvilinear core and tapered cladding has achieved the effect of improving strain performance of the sensor. Experimental results indicate that the CT-LPFG achieves a maximum strain sensitivity of −250.43 pm/με within 0–300 με. The sensor also exhibits a temperature sensitivity of 0.2 nm/℃. This structure combines high strain sensitivity with low manufacturing cost and easy fabrication.