Optimizing microstructured optical fibers for evanescent wave gas sensing

The relationships among the V parameter, confinement loss, relative sensitivity, operating wavelength and structural parameters of microstructured optical fibers for gas sensing applications are investigated theoretically. The V parameter of microstructured optical fibers and the confinement loss requirement set a limit on the maximum sensitivity achievable from index-guiding microstructured fibers. The maximum relative sensitivity is around 30–35%, corresponding to confinement losses of 0.1 dB/m and 1 dB/m, respectively. A novel fiber design to achieve faster sensor response is also proposed and analyzed.