125 μm fiber based all-optical ultrasound probes for pulse-echo imaging
All-optical ultrasound probe, which contains a photoacoustically based ultrasound generator paired with a photonic acoustic sensor, provide promising imaging modality for diagnostic and MRI compatible applications. Here, we demonstrate the fabrication of a fiber-based all-optical ultrasound probe and its application in pulse-echo ultrasound imaging. The ultrasound generator is fabricated on a 125-μm multimode optical fiber by forming a light-absorbing multiwalled carbon nanotubes (MWCNTs)-polydimethylsiloxane (PDMS) composite coating on its distal end. A peak-to-peak acoustic pressure 0.95 MPa has been achieved at nearly the damage threshold 2.46 μJ, by chemically functionalizing the fiber surface to enable strong nanotube adsorption. Ultrasound reception was performed by a fiber-laser ultrasound sensor which translates ultrasound pressure into differential lasing-frequency changes. By linearly scanning the probe, ex vivo two- and three-dimensional imaging of a segment of swine trachea has been demonstrated, by detecting the echo ultrasound signals and reconstructing the acoustic scatters. The probe presents axial and lateral resolutions at 150 and 62 μm, respectively. The small-sized, side-looking all-fiber ultrasound probe presents a promising approach for assembling an interventional endoscopy.
Zhang Yinlong,Liang YiZhi,Jin Long,Guan Bai-Ou. 125 μm fiber based all-optical ultrasound probes for pulse-echo imaging[J].Chinese Optics Letters,2019,17(7):07.