Abstract
In this work, we proposed and demonstrate an in-line cascaded eight-cores-fiber (ECF) sensor and tested the feasibility for wide range of ultrasound detection. The sensor is fabricated by directly cascaded two single mode fibers (SMF), two short step-index multimode fibers (MMF)and an ECF in the middle, and the ECF structure can effectively enhance the intensity of the mode-interference between core mode and higher-order modes. Thus, by simulating the transmission modes in ECF and analyzing transmission spectrum of sensors with different ECF lengths, an ultrasound sensor with the ECF length of 2.5 cm can be obtained. We constructed the ultrasound detection experimental system, and the experimental results show that the sensor can detect ultrasound signals with frequency from 25 kHz to 300 kHz, and have a high signal-to-noise ratio (maximal value of 76 dB). The ultrasound sensing sensitivity is calculated as 2.86 mV/kPa. The proposed sensor has compact structure and large measurement range, which shows the good potential in high sensitivity ultrasound detection.
Published Version
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