Black phosphorus-coated tilted fiber Bragg grating for ultrasensitive ion sensing

We propose an ultrasensitive ion sensor based on black phosphorus coated 81°-tilted fiber grating for Pb
²⁺
ion detection, demonstrating significant performance of ultrahigh sensitivity (8.6×10
^-5
dB/ppb), lower detection limit (0.4ppb) and wider concentration range (0.1ppb ~1.5×10
⁷
ppb).