Self-Enclosed Fiber-Optic Fabry-Pérot Sensor Based on Etched B-Ge Co-Doped Optical Fiber

An extrinsic optical fiber Fabry-Pérot sensor is fabricated by chemical etching of B-Ge co-doped optical fiber and electrical arc discharge. It is found that the etching rate of the fiber core is more than 30 times faster than that of the standard single-mode fiber when using 40% hydrofluoric acid as etching solution. Within the RI range of 1.350~1.400, the RI sensor has a sensitivity of ~30 dB/RIU and a resolution of ~3.33×10-5, with a linearity of >0.99. This low-cost method is suitable for mass production and has great potential for fabricating fiber-optic Fabry-Pérot sensors with long cavity lengths for use in spatial-frequency-division-multiplexing.