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).