Ultrasonic super-oscillation wave-packets with an acoustic meta-lens

Abstract

The Schrödinger equation is a fundamental equation to describe the wave function of a quantum-mechanical system. The similar forms between the Schrödinger equation and the paraxial wave equation allow a paradigm shift from the quantum mechanics to classical fields, opening up a plethora of interesting phenomena including the optical super-oscillatory behavior. Here, we propose an ultrasonic meta-lens for generating super-oscillation acoustic wave-packets with different spatial momenta and then superimposing them to a diffraction-limit-broken spot, visually represented by the ring-shaped trapping of tiny particles. Moreover, based on the focused super-oscillation packets, we experimentally verify proof-of-concept super-resolution ultrasound imaging, opening up the arena of super-oscillation ultrasonics for advanced acoustic imaging, biomedical applications, and versatile far-field ultrasound control.

Sharkskin-Inspired Magnetoactive Reconfigurable Acoustic Metamaterials

“…This study highlights a unique paradigm for applying stimuli-responsive smart materials to acoustic metamaterials and metadevices to enable active control of their acoustic properties [32,33]. This paradigm may promote the integration between various smart or soft materials and acoustic metamaterials to achieve unprecedented functionalities [53,54]. The unique paradigm may also promote the study of active acoustic metamaterials in switching of acoustic properties via other untethered stimuli, such as electric field, light, and temperature.…”

Efficiency-enhanced and sidelobe-suppressed super-oscillatory lenses for sub-diffraction-limit fluorescence imaging with ultralong working distance

“…Recently, a non-invasive and universal imaging technique without complex mathematical post-processing, called superoscillatory lens (SOL) optical microscopy, was proposed. [9][10][11][12][13][14][15] The optical super-oscillation phenomenon is the delicate interference of far-field propagating waves carrying the fine physical details of objects, and it can be accurately engineered to achieve sub-diffraction-limit foci, even smaller than the size defined as the super-oscillatory criterion 0.38λ/NA (where NA is numerical aperture). 16,17 However, the small super-oscillation hotspots are always accompanied by inevitably moderate sidelobes, 18 bringing a certain inconvenience for practical applications, especially in fields that do not need too small a hotspot but a wide enough effective field of view for optical imaging.…”

“…Notably, parallel fabrication of optical elements is becoming the main trend instead of the complex and time-consuming processes such as electron beam lithography (EBL) and focused ion beam etching (FIB). 15,[26][27][28][29] Recently, direct laser writing (DLW) lithography was employed to fabricate a planar lens, 30,31 but several square regions were joined together to acquire a hundreds of micrometers device and an apparent misalignment could be found. Through pushing the smallest line width of the planar SOLs up to tens of micrometers, we just realized centimeter-scale SOLs by employing the normal lithography process at the wafer level.…”

Super-resolution acoustic image montage via a biaxial metamaterial lens

“…In modern times, the development of montage and other image processing technologies has revolutionized various aspects of science and society. In terms of acoustic imaging, it has become a unique force widely deployed in various practical applications [1][2][3][4][5][6][7]. Corresponding image processing techniques were also proposed.…”