Miniature fiber pressure sensor based on fiber etching

A miniature fiber optic pressure sensor based on Fabry–Perot interference fabricated on the tip of a single mode (SM) fiber is presented. The sensor measures only 125 μm in diameter. A Fabry–Perot cavity and a thin silica diaphragm are fabricated by simple techniques involving only cleaving, wet chemical etching and fusion splicing. Interference pattern of the sensor is analyzed and issues in sensor design are discussed. The overall chemical reaction of the fiber wet etching is specifically represented. Pressure testing system is carried out. By tracing a peak point in the interference spectrum, the gap length of the sensor can be demodulated. Experimental results show the sensor has a good linearity. The sensor is made entirely of fused silica, whose structure has good stability, cabinet, simple for fabrication and low cost.