Bending-loss-compensated backscattering-enhanced fiber for distributed acoustic sensing

The distributed acoustic sensing (DAS) system can reach high sensitivity by wrapping the sensing fiber on an elastomer, however, the bending loss of sensing fiber limits the sensing range of DAS system. To solve this problem, we propose and fabricate a bending-loss compensated backscattering-enhanced fiber (BEF) for DAS based on continuous inscription of ultraweak fiber Bragg gratings and gradually increasing the backscattering along the G.657.A2 bend insensitive fiber (BIF). The SNR of DAS with bending-loss compensated BEF is 5dB higher than that with BIF, at a bending radius of 7.5 mm and bending turns of 200. The bending-loss compensated BEF can also extend the sensing range of DAS greatly under higher bending loss, which could release the contradiction between sensing distance and sensitivity of DAS.