Abstract

We report on a dual-fiber ultrasound probe for pulse-echo imaging. For ultrasound generation, a fiber is coated with a highly absorptive overlay made of carbon nanotube composite at its distal end. Ultrasound waves with a peak-to-peak amplitude of over 2.5 MPa can be photothermally generated by injecting nanosecond laser pulses. The scattered ultrasound waves at the specimen are detected by a paired fiber-laser-based ultrasound sensor, by translating the pressure waves into the variation of lasing frequencies. The probe has a diameter of 2.5 mm and an ultrasound spectrum centered at 22 MHz, and 90% -6 dB bandwidth. Ex vivo ultrasound imaging of a biological tissue has been performed with axial and lateral resolutions at 150 and 62 μm, respectively, by linearly scanning the probe, detecting the scattered waves and then forming an image via back projection. The all-fiber ultrasound probe offers an alternative approach towards next-generation intravascular and gastroenterological endoscopes.

© 2020 The Author(s)