Sub-diffraction-limit optical needle can be created by a binary amplitude mask through tailoring the interference of diffraction beams. In this paper, controllable design super-oscillatory planar lenses to create sub-diffraction-limit needles with tunable focal length and depth focus (DOF) is presented. As high-quality influenced various factors, we first propose multi-objective multi-constraint optimization model compromising all main factors achieve prescribed characteristics. The...

Metasurface-based flat optics is continuously attracting interest owing to its ability for miniaturization of optical devices and systems. Over the last few years, broadband achromatic metalenses have been extensively studied focusing imaging in visible band. However, it still a substantial challenge design an metalens that can produce high-focusing efficiency high-consistency focal length over entire spectrum. In this Letter, we propose polarization-independent operating at wavelengths from...

The conventional multifocal optical elements cannot precisely control the focal number, spot size, as well energy distribution in between. Here, binary amplitude-type super-oscillatory lens (SOL) is utilized, and a robust universal optimization method based on vectorial angular spectrum (VAS) theory genetic algorithm (GA) proposed, aiming to achieve required focusing performance with arbitrary number of foci preset distribution. Several typical designs SOLs are demonstrated. Verified by...

A flexible broadband absorber based on an all-dielectric multilayer structure is proposed to get average absorbance of 97.4%, covering the whole visible light. Additionally, such high absorption presents extraordinary angular tolerance up <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>±</mml:mo> </mml:mrow> <mml:msup> <mml:mn>50</mml:mn> <mml:mo>∘</mml:mo> </mml:msup> </mml:math> . Due single resonance in highly lossy...

The imaging capability of conventional lenses is mainly limited by the diffraction light, and so-called superlens has been developed allowing recovery evanescent waves in focal plane. However, remarkable focusing behavior greatly confined near-field regime due to exponential decay waves. To tackle this issue, we design a waveguide metasurface-based with an extraordinary quasi-far-field beyond limit present work. Specifically, analyze underlying physical mechanism provide experimental...

For conventional refractive lenses, chromatic aberration inevitably occurs due to the index variation of lens material with incident wavelength, leading axial aberrations and lower imaging system quality. Achromatic metalenses have demonstrated a great capability solve this problem been extensively investigated. However, metalens achromatic method involves construction unit structure satisfying phase distribution greater than 0-2

Metalenses provide unprecedented opportunities to overcome the limitations of conventional refractive lenses, which have been extensively studied achieve achromatic focusing and imaging in various wavebands. However, it is a challenging task create metalens that can with high efficiency for broad bandwidth covering entire visible near-infrared spectrum. Here, we present design difficulty by employing two types silicon nitride pillars different cross sections as optical phase shifters....

The films of vinylidene fluoride and trifluoroethylene (P(VDF-TrFE)) are widely used in piezoelectric tactile sensors, vibration energy harvesters, optical frequency conversion materials organic photo-voltaic devices because high electroactive, good nonlinear properties, respectively. In this work, the multilayer structured ultrathin were fabricated by Langmuir–Blodgett technique, thickness per layer can be controlled accurately. It was found that as collapse pressure P(VDF-TrFE) (25:75)...

We report a metallic planar lens based on the coupled nanoslits with variable widths for superfocusing. The influence of interaction between two adjacent phase delay is systematically investigated using finite-difference time-domain (FDTD) method. Based geometrical optics and wavefront reconstruction theory, an array perforated in gold film optimally designed to achieve desired modulation light beaming. simulation result verifies our design excellent agreement realized reveals superfocusing...

Slit arrays based on noble metals have been widely proposed as planar transverse-magnetic (TM)-lenses, illuminated by a linearly polarized light with the polarization perpendicular to slits and implementing focusing capability beyond diffraction limit. However, due intrinsic plasmonic losses, these TM-lenses cannot work efficiently in ultraviolet wavelengths. In this Letter, taking advantage of unique transmission through metallic not involving slit array transverse-electric (TE)-polarized...

In this paper, synthetically using refraction, diffraction, and interference effects to achieve free manipulation of the focused optical field, we firstly present a photonic nanojet (PNJ) generated by micropyramid, which is combined with multilayer thin films. The theory total internal reflection (TIR) was creatively used design base angle size parameters material properties microstructure were deduced via expected field distribution. as-designed bilayer micropyramid array fabricated...

The development of techniques for efficiently confining energy in the visible and infrared spectral regions to deep subwavelength spatial scale with dimensions as small a few nanometers would have great significance scientific research engineering practices. Such an ability manipulate light is impossible conventional dielectric lenses due diffraction limit. Here, we propose metallic graded-index (MGRIN) lens formed by array coupled waveguides identical nanoscale widths embedded index-varying...

Conventional optics suffer from the diffraction limit. Our recent work has predicted a nanoslit-based two-dimensional (2D) lens with transverse-electric (TE) polarized design that is capable of realizing super-resolution focusing light beyond limit in quasi-far field. Furthermore, capability can be kept high-refractive-index dielectric over wide wavelength range ultraviolet to visible light. Here, we systematically investigate influence various factors on performance lens. Factors such as...

Flat all-silicon metasurfaces have significant potential as ultrathin optical devices and systems that offer the advantages of mature fabrication technology complementary metal–oxidesemiconductor compatibility. However, previously reported suffered from drawback low transmission owing to large intrinsic reflection loss induced by high-index silicon substrates. To achieve high transmission, silicon-based are usually composed low-index dielectric substrates pillars. It is still a substantial...

The two-dimensional superfocusing of nanoring-based plasmonic lenses (NRPLs) beyond the diffraction limit in far-field region remains a great challenge at optical wavelengths. In this paper, addition to modulation structural parameters, we investigated polarization-dependent focusing performance NRPL employing finite-difference time-domain (FDTD) method. By utilizing state polarization (SOP) incident light, successfully realize elliptical-, donut-, and circular-shape foci. minimum full...

The microlens arrays (MLAs) are widely utilized for various applications. However, when the lens size and spacing between two adjacent microlenses of length scale working wavelength, diffraction effect plays a vital role in final focusing performance. We suggest kind broadband metallic planar microlenses, based on which ultra-compact also constructed. coupling revealing such devices is then investigated detail by using finite-difference time-domain (FDTD) method, with emphasis changing...

We present a conceptual demonstration of metallic planar lens composed double-turn waveguides for sub-diffraction-limit focusing. The phase delay single waveguide dependent on its structural parameters is investigated by employing the finite-difference time-domain (FDTD) numerical method. design utilizes surface plasmon polaritons (SPPs) that propagate along metal-insulator-metal (MIM) to achieve desired spatial modulation in transmitted field. simulated focal length achieved positive...

A novel low-cost, batch-fabrication method combining the spin-coating nanosphere lithography (NSL) with conventional photolithographic technique is demonstrated to efficiently produce metallic planar microlenses and their arrays. The developed are composed of subwavelength nanoholes can focus light effectively in entire visible spectrum, foci sizes close Rayleigh diffraction limit. By changing spacing diameter nanoholes, focusing efficiency be tuned. Although random defects commonly exist...

Planar optical components formed by metasurfaces show excellent ability in achromatic design. However, designing ultra-broadband metalenses, integrating multiple types of unit structures is necessary to compensate for phase differences caused different incident wavelengths. This requirement increases the complexity both design and manufacturing processes. Here, we propose an metalens composed only a single type squre nano-pillars, which controls entire operating band with three sub-bands....