Bend and refractive index sensing based on the tuning fork fiber
In this paper, a simple, low-cost, and high-sensitivity optical fiber bend/RI sensor based on the tuning fork fiber is proposed. The new fiber is based on the mode-coupling theory of two cores that contiains two non parallel cores in the bending sensor or parallel cores in the RI sensor. The operation principle relies on the power coupling of two cores inputted into light simultaneously. This tuning fork fiber is ease of fabrication, low cost, and simple signal acquisition, since no spectral manipulations are required, which enormously decreases the sensor cost and has greater practical value and innovative significance. The sensitivity of the proposed fiber to bending and external refractive index is investigated. The beam propagation analysis and structural impact of bending and RI sensor are performed. The propagation numerical simulations with a full vectorial BPM demonstrate that it allows highly accurate curvature and refractive index detection. The bending sensitivity is about 0.01184W/m?1 at curvatures ranging from 0 to 50m?1, the RI sensitivity is about ?1.5557, ?22.3031 and ?102.44878W/RIU at refractive indexes ranging from 1.331.418, 1.4181.45 and 1.451.456, respectively.
tuning fork fiber bend sensor refractive index sensor