A Simplified Fabrication Technique for Tilted Fiber Bragg Grating for The Simultaneous Measurement of Refractive Index and Temperature of Liquids

We have developed a simplified technique to fabricate tilted fiber Bragg gratings (TFBGs) for simultaneous measurement of the refractive index and temperature of liquids in biochemical and medical applications. We used a combination of a 4 Nd:YAG laser and a phase mask, which is simpler than the conventional method using a 2 cw Ar + laser and a Lloyd mirror interferometer. The peak of the cladding mode of the TFBG shifted to the longer wavelength side as the refractive index of liquid increased. Furthermore, both the peak of the cladding mode and that of the core mode shifted to the longer wavelength side as the temperature of liquid increased. We found that a refractive index from 1 to 1.41, and a temperature from 293 to 353 K could be measured with a single probe of the fabricated TFBGs.