All-optically controlled phased-array for ultrasonics.

The ability to dynamically shape ultrasound fields is critical for emerging applications in therapeutic ultrasound, particle manipulation and tissue engineering. While existing phased arrays provide beam steering for imaging, these newer applications require higher intensities. This complicates the electrical driving and ultimately limits the array size and spatial complexity of the field. Here, we introduce a scalable architecture for driving phased arrays using a single power source and light-responsive analog phase shifters. Compared to conventional arrays, which drive each channel independently, our device only needs one amplifier. Moreover, the phase shift can be continuously varied between  ±π based on light intensity. Using our phase shifter, we demonstrate dynamic, multi-focal ultrasound beams, fast beam steering, and spatially-complex beams including acoustic vortices. Because of its simple, analog design, optical addressing, and superior phase control, this architecture paves the way for very large transducer arrays and the generation of high-intensity, spatially-complex ultrasound fields.