Fiber-optic acoustic and pressure sensors with ultra-high sensitivity

Pressure/acoustic sensors based on a hollow-core photonic bandgap fiber (HC-PBF) with thin outer-cladding and a fiber-tip micro-cavity with ultra-thin graphene diaphragm are reported. The HC-PBF sensor demonstrates a normalized acoustic responsivity of ~25 dB higher than standard single mode fiber while the fiber-tip sensor has a record high pressure responsivity of well over 1000 nm/kPa.