Miniature fiber-optic pressure sensor

This letter presents a miniature fiber-optic pressure sensor fabricated directly on the tip of a fiber. The sensor measures only 125 mum in diameter. A Fabry-Perot cavity and a thin silica diaphragm are fabricated by simple techniques involving only fusion splicing, cleaving, and wet chemical etching. Interference pattern of the sensor is analyzed and issues in sensor design are discussed. The sensor has been tested for static pressure response, showing excellent repeatability and no hysteresis. Its all-fused-silica structure lends it great potential for high-temperature pressure measurements. Pressure testing results at 530 degreesC are given. The sensor may also find uses in medical applications.