Dispersion compensated spectral demodulation method for silicon-based Fabry-Pérot interferometric temperature sensors

The spectral demodulation method has been widely used in the interrogation of Fabry-Pérot (F-P) temperature sensors due to its high accuracy and large dynamic range, yet the dispersion of the cavity materials could lead to the failure of the calculation. A dispersion compensated spectral demodulation method for the fiber optical Silicon-based F-P temperature sensor was proposed in this article. The numerical model of the Silicon sensing F-P cavity was built using the thermal expansion and thermos-optic characteristics of the material, from which a compensation curve was proposed to counteract the dispersion-induced optic path difference (OPD) blue shift, in order to correctly solve the cavity’s OPD. Simulations showed that this method doesn’t introduce any degradation of precision compared to the traditional spectral demodulation method. The experiment also proved that the method avoided the dispersion-induced phase jump defects during the temperature experiment, which ranged from -40 to 100 °C. The proposed method guarantees the effective application for the use of spectral demodulation method in the silicon-based F-P temperature sensors.