Optical superoscillatory waves without side lobes along a symmetric cut

Abstract

Optical superoscillation refers to an intriguing phenomenon of a wave packet that can oscillate locally faster than its highest Fourier component, which potentially produces an extremely localized wave in the far field. It provides an alternative way to overcome the diffraction limit, hence improving the resolution of an optical microscopy system. However, the optical superoscillatory waves are inevitably accompanied by strong side lobes, which limits their fields of view and, hence, potential applications. Here, we report both experimentally and theoretically a new superoscillatory wave form, which not only produces significant feature size down to deep subwavelength, but also completely eliminates side lobes in a particular dimension. We demonstrate a new mechanism for achieving such a wave form based on a pair of moonlike sharp-edge apertures. The resultant superoscillatory wave exhibits Bessel-like forms, hence allowing long-distance propagation of subwavelength structures. The result facilitates the study of optical superoscillation and on a fundamental level eliminates the compromise between the superoscillatory feature size and the field of view.

Design for Highly Efficient Nanometagratings and Theory of Extreme Subdiffraction Photon Control

“…Even though, due to the apodization of the strong sidelobes, these ratios are at least several orders of magnitude higher than that of traditional superoscillations lenses with similar resolution. [13][14][15][16] These ratios ξ will increase with the number of the pixels N in both cases, as clearly shown in Figure 4e. For example, in the first case when N=2ðn þ 1Þ ¼ 2, ξ soon reaches 0.69, and the corresponding width of the pixel is 5 nm when we still choose λ to be 520 nm.…”

“…However, conventional wisdom based on the Fourier-based planewave propagation theories has also suggested that the efficiency of such metasurfaces is extremely poor, as strong sidelobes capturing almost all the energy passing through the boundary are always in company with these superoscillatory features. [13][14][15][16] Moreover, this "energy leakage" is known to be fundamentally related to the "space-bandwidth product" of these superoscillatory functions, suggesting that it will become much more severe when the size of the metasurfaces is small, and there is a fundamental tradeoff between the size and the overall conversion efficiency of any diffraction-based metasurfaces. [14] Here, we propose the theory of extreme subdiffraction photon control.…”

Helmholtz-Structured Two-Dimensional Super-Diffraction Meta-Lens

“…The energy of the main lobe is higher than the sidelobe in the focusing plane, and the acoustic meta-lens has a subwavelength spatial resolution beyond the diffraction limit. Based on the Rayleigh-Somerfield (RS, Rayleigh-Somerfield) theory in the optical theory system [ [33][34][35]], the formula for the diffraction sound field (z > 0) beyond the acoustic metalens structure can be expressed as…”

On‐Demand Subwavelength‐Scale Light Sculpting Using Nanometric Holograms

“…[16][17][18][19][20] This structured light is characterized by a helical wavefront and exhibits inhomogeneous polarization, leading to intriguing applications in the emulations of quantum processes. [21,22] Another featured examples include the Bessel beam, [23][24][25] Airy beam, [26][27][28][29][30] and recently reported pendulum-type beam, [31] which propagates (accelerates) along arbitrary trajectory in 3D space without diffraction and disintegration. The structured light has been applied to control nanostructures (particles), [32,33] Bose-Einstein condensates, [34] electric currents, [35] etc., and led to intriguing spin-orbit couplings when the structured light meets structured materials.…”

“…[45][46][47] Yet for many years, the challenges have been generally to remove the unwanted strong sidelobes from the superoscillatory light patterns. [25,48] In addition, photonic structures such as subwavelength angular gratings, [49] waveguide arrays, [50] metamaterials, [51] can significantly squeeze the light field into extremely small scale; however, they only support several specific light modes that are difficult to be tuned; [52] if these subwavelength modes emit from the structure to free space, they exhibit serious diffraction and expand rapidly during propagation. We emphasize that the diffraction limit restricts spot size of light to about half the wavelength.…”