Pressure sensor based on mode field variation of a photonic crystal fiber

We propose a simple and novel temperature-insensitive pressure sensing technology based on the variation of the mode field diameter (MFD) of the fundamental mode in a photonic crystal fiber (PCF). When external pressure is applied, the geometry dimension of the PCF cross-section and hence the mode field of the fundamental mode will change. This results in variation in coupling loss at the joint between the PCF and a conventional singe mode fiber (SMF). By measuring the transmission loss of the joint, the applied pressure can be determined. Numerical simulation shows that the MFD of the PCF and the joint loss between the PCF and the SMF have linear relationship with the applied pressure, and the slope of the loss-pressure curve is 1.75 %/MPa. The sensor is simple and of very low cost and may be used for high pressure measurement in harsh environment.