Photonic crystal fibre sensor for alcohol detection with extremely low birefringence

A photonic crystal fibre (PCF) based alcohol sensor with extremely low birefringence has been proposed for different alcohol analytes of propanol, butanol and pentanol, operating within 0.8 to 2.0 μm wavelength. A structural design of three layers of circular cladding air holes with three elliptical core holes has been designed and simulated to distinguish the capabilities of the PCF as a sensor, which accomplished high relative sensitivity, low confinement loss and extremely low birefringence. At the examined optimum wavelength of 0.8 μm, the assessed relative sensitivities are 93.3%, 88.7% and 82.2% for propanol, butanol and pentanol, respectively, and confinement losses of 9.80 × 1/1013 dB/m for propanol, 4.91 × 1/1013 dB/m for butanol and 1.03 × 1/1013 dB/m for pentanol. The birefringence of the proposed PCF is about 0.0001 for all the selected test analytes. Moreover, considering the simple cross-sectional design, it shall be easily fabricated for practical alcohol detection.