Huapeng Ye

Theoretical realization of robust broadband transparency in ultrathin seamless nanostructures by dual blackbodies for near infrared light

We propose a counter-intuitive mechanism of constructing an ultrathin broadband transparent device with two perfect blackbodies. By introducing hybridization of plasmon modes, resonant modes with different symmetries coexist in this system. A broadband transmission spectrum in the near infrared regime is achieved through controlling their coupling strengths, which is governed by the thickness of high refractive index layer. Meanwhile, the transparency bandwidth is found to be tunable in a large range by varying the geometric dimension. More significantly, from the point view of applications, the proposed method of achieving broadband transparency can perfectly tolerate the misalignment and asymmetry of periodic nanoparticles on the top and bottom, which is empowered by the unique dual of coupling-in and coupling-out processes within the pair of blackbodies. Moreover, roughness has little influence on its transmission performance. According to the coupled mode theory, the distinguished transmittance performance is physically interpreted by the radiative decay rate of the entire system. In addition to the feature of uniquely robust broadband transparency, such a ultrathin seamless nanostructure (in the presence of a uniform silver layer) also provides polarization-independent and angle-independent operations. Therefore, it may power up a wide spectrum of exciting applications in thin film protection, touch screen techniques, absorber-emitter transformation, etc.

Manipulating DC currents with bilayer bulk natural materials.

A novel and general method for spatially manipulating DC currents has been proposed and experimentally verified by only using bilayer bulk natural conductive materials. Our approach shows distinctive advantages with respect to homogeneity, isotropy, and independence of complicated microfabrication techniques. Our design scheme can be readily extended to robust manipulations of magnetic fields, thermal heat, elastic mechanics, and matter waves.

Manipulation of acoustic focusing with an active and configurable planar metasurface transducer

It has a pivotal role in medical science and in industry to concentrate the acoustic energy created with piezoelectric transducers (PTs) into a specific area. However, previous researches seldom consider the focal resolution, whose focal size is much larger than one wavelength. Furthermore, there is to date no such design method of PTs that allows a large degree of freedom to achieve designed focal patterns. Here, an active and configurable planar metasurface PT prototype is proposed to manipulate the acoustic focal pattern and the focal resolution freely. By suitably optimized ring configurations of the active metasurface PT, we demonstrate the manipulation of focal patterns in acoustic far fields, such as the designed focal needle and multi foci. Our method is also able to manipulate and improve the cross-sectional focal resolution from subwavelength to the extreme case: the deep sub-diffraction-limit resolution. Via the acoustic Rayleigh-Sommerfeld diffraction integral (RSI) cum the binary particle swarm optimization (BPSO), the free manipulation of focusing properties is achieved in acoustics for the first time. Our approach may offer more initiatives where the strict control of acoustic high-energy areas is demanding.

Creation of a longitudinally polarized subwavelength hotspot with an ultra-thin planar lens: vectorial Rayleigh-Sommerfeld method

This letter shows how a longitudinally polarized hotspot can be created by a planar ultra-thin lens that beats the diffraction limit. On the imaging plane, a subwavelength optical resolution 0.39λ with almost purely longitudinal electric component has been demonstrated in air ambient. This novel paradigm addresses simultaneously both longitudinal polarization and deep sub-diffraction imaging, by a planar lens composed of ultra-thin opaque concentric annuli. The vectorial Rayleigh–Sommerfeld (VRS) approach, offering the advantage of significant reduction in computation, has been developed for a particular optimization of a flat lens with full control of polarization. Empowered by the robustness of VRS in dealing with polarization states, the proposed roadmap may be universally and efficiently integrated with other optimization algorithms to design super-resolution imaging with controlled polarization states at any wavelength without luminescence of the object. The lens, which is empowered by the proposed method, opens an avenue for the first time toward a highly integrated imaging system with advanced functionalities in far-field super-imaging, tailored polarization states and flat ultra-thin geometry simultaneously.

Creation of vectorial bottle-hollow beam using radially or azimuthally polarized light

We propose a single-beam generation scheme to obtain a bottle-hollow (BH) beam using a binary phase mask and a focusing lens. The resulting BH beam is shown to possess an open bottle-shaped null intensity region, which has two hollow tube-shaped null intensity regions located on two opposite sides of this bottle. It is found that this scheme works identically under incident illumination with radial or azimuthal polarization. Another advantage of this scheme is that the same binary mask can be employed as a focusing lens with different choices of numerical aperture (NA). Furthermore, we observe that the length of the BH beam is inversely proportional to NA2 while the diameters of both the bottle and hollow regions are inversely proportional to NA; thereby leading to an adjustable BH beam. This BH beam may find attractive applications in noninvasive manipulation of microscopic particles over large distances.

Three-dimensional supercritical resolved light-induced magnetic holography

3D supercritical resolved light-induced magnetic holography makes possible 1872 Tbit/in3 ultrahigh-density data recording. In the era of big data, there exists a growing gap between data generated and storage capacity using two-dimensional (2D) magnetic storage technologies (for example, hard disk drives), because they have reached their performance saturation. 3D volumetric all-optical magnetic holography is emerging rapidly as a promising road map to realizing high-density capacity for its fast magnetization control and subwavelength magnetization volume. However, most of the reported light-induced magnetization confronts the problems of impurely longitudinal magnetization, diffraction-limited spot, and uncontrollable magnetization reversal. To overcome these challenges, we propose a novel 3D light-induced magnetic holography based on the conceptual supercritical design with multibeam combination in the 4π microscopic system. We theoretically demonstrate a 3D deep super-resolved (~λ359) purely longitudinal magnetization spot by focusing six coherent circularly polarized beams with two opposing high numerical aperture objectives, which allows 3D magnetic holography with a volumetric storage density of up to 1872 terabit per cubic inches. The number and locations of the super-resolved magnetization spots are controllable, and thus, desired magnetization arrays in 3D volume can be produced with properly designed phase filters. Moreover, flexible magnetization reversals are also demonstrated in multifocal arrays by using different illuminations with opposite light helicity. In addition to data storage, this magnetic holography may find applications in information security, such as identity verification for a credit card with magnetic stripe.

FINITE-BOUNDARY BOWTIE APERTURE ANTENNA FOR TRAPPING NANOPARTICLES

We have found that a single flnite-boundary bowtie aperture (FBBA) antenna with gap separation of 10nm between its tips is capable of conflning the electric fleld to a 18nm £ 18nm region (‚=39:4) at 5nm beneath the gold fllm and enhancing its near- fleld intensity by 1,800-fold inside the gap. The FBBA antenna is thus able to provide enhanced trapping potential by virtue of such extraordinarily high (but exponentially decaying) optical near-flelds. We have been able to show that 12nm gold nanoparticles can, in principle, be trapped by the FBBA antenna with 20nm gap separation; stable trapping is assured where the trapping potential is found to be several times higher than Brownian-motion potential in water. In addition to trapping nanoparticles, this simple but e-cient FBBA antenna may flnd application in near-fleld optical data storage.

Optically induced atomic lattice with tunable near-field and far-field diffraction patterns

Conventional periodic structures usually have nontunable refractive indices and thus lead to immutable photonic bandgaps. A periodic structure created in an ultracold atoms ensemble by externally controlled light can overcome this disadvantage and enable lots of promising applications. Here, two novel types of optically induced square lattices, i.e., the amplitude and phase lattices, are proposed in an ultracold atoms ensemble by interfering four ordinary plane waves under different parameter conditions. We demonstrate that in the far-field regime, the atomic amplitude lattice with high transmissivity behaves similarly to an ideal pure sinusoidal amplitude lattice, whereas the atomic phase lattices capable of producing phase excursion across a weak probe beam along with high transmissivity remains equally ideal. Moreover, we identify that the quality of Talbot imaging about a phase lattice is greatly improved when compared with an amplitude lattice. Such an atomic lattice could find applications in all-optical switching at the few photons level and paves the way for imaging ultracold atoms or molecules both in the near-field and in the far-field with a nondestructive and lensless approach.

Planar Diffractive Lenses: Fundamentals, Functionalities, and Applications

Traditional objective lenses in modern microscopy, based on the refraction of light, are restricted by the Rayleigh diffraction limit. The existing methods to overcome this limit can be categorized into near-field (e.g., scanning near-field optical microscopy, superlens, microsphere lens) and far-field (e.g., stimulated emission depletion microscopy, photoactivated localization microscopy, stochastic optical reconstruction microscopy) approaches. However, they either operate in the challenging near-field mode or there is the need to label samples in biology. Recently, through manipulation of the diffraction of light with binary masks or gradient metasurfaces, some miniaturized and planar lenses have been reported with intriguing functionalities such as ultrahigh numerical aperture, large depth of focus, and subdiffraction-limit focusing in far-field, which provides a viable solution for the label-free superresolution imaging. Here, the recent advances in planar diffractive lenses (PDLs) are reviewed from a united theoretical account on diffraction-based focusing optics, and the underlying physics of nanofocusing via constructive or destructive interference is revealed. Various approaches of realizing PDLs are introduced in terms of their unique performances and interpreted by using optical aberration theory. Furthermore, a detailed tutorial about applying these planar lenses in nanoimaging is provided, followed by an outlook regarding future development toward practical applications.

Intrinsically shaping the focal behavior with multi-ring Bessel-Gaussian beam

Traditional manipulation of light generally employs diffractive optical elements such as binary phase or amplitude masks. However, we have found that vector Bessel-Gaussian (BG) beams have the intrinsic capacity of forming a special intensity pattern without additional optical elements. Using the vector diffraction theory, we theoretically show that several optical patterns (e.g., hollow beam, bottle beam, optical needle, and spot) can be created only by dynamically tailoring vector BG beams through their beam parameters (viz., polarization order n, transverse wave number β, and beam waist w0). These results yield a useful guideline for the adjustable beam parameter to generate a certain optical pattern in the focal region. The proposed roadmap of manipulating the structured beams by their intrinsic properties might open an alternative avenue for beam shaping.