Refractive index sensor with acoustic grating in a low index contrast photonic bandgap fiber

We demonstrate and optimize a microfluidic refractive index sensor with ultra-high sensitivity based on an acoustic grating in a solid core photonic bandgap fibre. The sensitivity of the acoustic grating's resonance is 18 000 nm/RIU which corresponds to smallest detectable changes in refractive index of 8.4×10
⁻⁶
.