Table 4.

FBG-based ultrasound sensors.

Ultrasonic	Coupling Method	SNR	Frequency Bandwidth
PS-FBG	Fiber end-face	19.55 dB	20 kHz~10 MHz
FBG-FP	Etched FBG-FP	27.96 dB	20 kHz~7.5 MHz
FBG	Cone end-face	32.57 dB	20 kHz~2 MHz