Note: Improving distributed strain sensing sensitivity in OFDR by reduced-cladding single mode fiber.

We present a method to improve distributed strain sensing sensitivity by a reduced-cladding single mode fiber (RC SMF) using a Rayleigh backscattering spectra shift in optical frequency domain reflectometry. Comparing with a standard SMF with 250 μm diameter, a commercial low attenuation RC SMF with 165 μm diameter is shown to enhance the strain sensing sensitivity by about four-fold. Using this property, the system using the RC SMF can achieve smaller minimal measurable strain (MMS) in the same sensing spatial resolution (SSR) or smaller SSR in the same MMS than using the standard SMF. In our experiment, the system using RC SMF can achieve the MMS of 15 μstrain with a SSR of 4.5 cm or the MMS of 3 μstrain with a SSR of 18 cm.