Temperature-Compensated Interferometric High-Temperature Pressure Sensor Using a Pure Silica Microstructured Optical Fiber

We present a high-temperature interferometric pressure sensor using a simple-design and easy-to-fabricate pure silica four-hole novel microstructured optical fiber. The asymmetric geometry of the fiber allows hydrostatic pressure to induce stress at the optical fiber core, which converts to an interferometric shift. The large core of the fiber supports the propagation of several modes. Multimode interference created between different pairs of modes is used to sense the temperature and pressure change. The use of pure silica fiber is motivated by the ability of this fiber to operate up to high temperature as dopant diffusion is avoided. The sensor is demonstrated to measure pressure at a temperature up to 800 degrees C. We demonstrate temperature compensation using a Fourier approach to monitor different interference pairs and their phase response to pressure and temperature change. Experimental results show that the sensor has a linear response and excellent stability with a detection limit of 8.86 kPa at 800 degrees C temperature. This simple, compact, and potentially low-cost sensor is promising for harsh environment applications to improve quality control, operation efficiency, and safe working conditions.