Optical Ultrasound Generation and Detection for Intravascular Imaging: A Review

Table 3

Summary of performance characteristics of optical ultrasound detectors.

Sensor	Geometry	Detection direction	Diameter (μm)	Sensitivity (kPa)	Bandwidth (MHz)
FP etalon [36]	Cylindric cavity	Forward	6–10	15	20
FP etalon [37]	Concave cavity	Forward	125	0.4	20
FP etalon [38]	Dual cladding	Forward	—	—	—
FP etalon [38]	Dual cladding	Sideway	—	—	—
FP etalon [39]	Planoconcave cavity	Forward	5.2	0.093	40
Microring [41]	Ring	Forward	100	0.23	75
Microring [40]	Ring	Sideway	~800	0.352	250
FBG [42]	Cylindric grating	Sideway	-/(270 in length)	0.44	10
FBG [43]	Cylindric grating	Forward	-/(1500 in length)	9 nε/Hz^1/2	—

Noise equivalent pressure (NEP), the acoustic pressure with which signal-to-noise ratio equals 1, is used as the criterion to evaluate detectors. Forward refers to the axial direction of the optical fiber while sideway refers to the radial direction.