PDMS-Coated S-Tapered Fiber for Highly Sensitive Measurements of Transverse Load and Temperature

A novel highly sensitive fiber sensor for transverse load and temperature measurement has been fabricated by polydimethylsiloxane (PDMS) packaging an S fiber taper (SFT). The PDMS coating is an effective transverse load and temperature transducer due to its material characteristics, such as low Young´s modulus, high Poisson´s ratio, and large thermooptic coefficient, which can efficiently transfer the lateral force into axial tension on the SFT or convert temperature into refractive index (RI) change around SFT. Because the SFT is highly sensitive to axial strain and surrounding RI, the PDMS-coated SFT will have high sensitivities of transverse load and temperature, which have been experimentally obtained up to -29.03 nm/N and -2.17 nm/°C, respectively. In addition, to solve the problem of cross sensitivity, two-wavelength demodulation method has been proposed for simultaneous measurement of transverse load and temperature.