Highly birefringent photonic bandgap Bragg fiber loop mirror for simultaneous measurement of strain and temperature.

A highly birefringent photonic bandgap Bragg fiber loop mirror configuration for simultaneous measurement of strain and temperature is proposed. The group birefringence and the sharp loss peaks are observable in the spectral response. Because the sensing head presents different sensitivities for strain and temperature measurands, these physical parameters can be discriminated by using the matrix method. It should be noted that this Bragg fiber presents high sensitivity to temperature, of ∼5.75 nm/°C, due to the group birefringence variation. The rms deviations obtained are ±19.32 με and ±0.5 °C, for strain and temperature measurements, respectively.