Abstract
We demonstrated that a simple technique combining a 266-nm laser and a phase mask was quite effective
at fabricating tilted fi ber Bragg gratings (TFBG) for refractive index sensor of liquids. Using fabricated
TFBGs that have the tilted angles of 3.3, 6.7, 7.3, 8.0, and 9.9 °, we tried to measure the refractive
index of liquids that have different indices. We have directed our attention to the fact that the wavelength
of cladding mode becomes longer as the refractive index of sample liquids increases. Utilizing
this wavelength shift, we proposed a new measurement method. As a result, we could successfully measure
the refractive index of liquids within a range from 1.00 to 1.41 with a maximum resolution of
2.1 × 10－3. In addition, we have found that a writing length only 2 mm long is enough for measuring
the refractive index of liquid.
