Ultraviolet (UV) optical devices have plenteous applications in the fields of nanofabrication, military, medical, sterilization, and others. Traditional optical components utilize gradual phase accumulation phenomena to alter the wave-front of the light, making them bulky, expensive, and inefficient. A dielectric metasurface could provide an auspicious approach to precisely control the amplitude, phase, and polarization of the incident light by abrupt, discrete phase changing with high efficiency due to low absorption losses. Metalenses, being one of the most attainable applications of metasurfaces, can extremely reduce the size and complexity of the optical systems. We present the design of a high-efficiency transmissive UV metalens operating in a broadband range of UV light (250-400 nm) with outstanding focusing characteristics. The polarization conversion efficiency of the nano-rod unit and the focusing efficiency of the metasurface are optimized to be as high as 96% and 77%, respectively. The off-axis focusing characteristics at different incident angles are also investigated. The designed metalens that is composed of silicon nitride nanorods will significantly uphold the advancement of UV photonic devices and can provide opportunities for the miniaturization and integration of the UV nanophotonics and its applications.
Airy optical beams have emerged to hold enormous theoretical and experimental research interest due to their outstanding characteristics. Conventional approaches suffer from bulky and costly systems, as well as poor phase discretization. The newly developed metasurface-based Airy beam generators have constraints of polarization dependence or limited generation efficiency. Here, we experimentally demonstrate a polarization-independent silicon dielectric metasurface for generation of high-efficiency Airy optical beams. In our implementation, rather than synchronous manipulation of the amplitude and phase by plasmonic or Huygens’ metasurfaces, we employ and impose a 3/2 phase-only manipulation to the dielectric metasurface, consisting of an array of silicon nanopillars with an optimized transmission efficiency as high as 97%. The resultant Airy optical beams possess extraordinarily large deflection angles and relatively narrow beam widths. Our validated scheme will open up a fascinating doorway to broaden the application scenarios of Airy optical beams on ultracompact photonic platforms.
Metasurfaces in the ultraviolet spectrum have stirred up prevalent research interest due to the increasing demand for ultra-compact and wearable UV optical systems. The limitations of conventional plasmonic metasurfaces operating in transmission mode can be overcome by using a suitable dielectric material. A metalens holds promising wavefront engineering for various applications. Metalenses have developed a breakthrough technology in the advancement of integrated and miniaturized optical devices. However, metalenses utilizing the Pancharatnam–Berry (PB) phase or resonance tuning methodology are restricted to polarization dependence and for various applications, polarization-insensitive metalenses are highly desirable. We propose the design of a high-efficiency dielectric polarization-insensitive UV metalens utilizing cylindrical nanopillars with strong focusing ability, providing full phase delay in a broadband range of Ultraviolet light (270–380 nm). The designed metalens comprises Silicon nitride cylindrical nanopillars with spatially varying radii and offers outstanding polarization-insensitive operation in the broadband UV spectrum. It will significantly promote and boost the integration and miniaturization of the UV photonic devices by overcoming the use of Plasmonics structures that are vulnerable to the absorption and ohmic losses of the metals. The focusing efficiency of the designed metalens is as high as 40%.
In symmetric nano/micro metal slit structures, interference patterns are produced by counter-propagating surface plasmon polaritons (SPPs) in the the center of structures, which can be employed to improve the resolution of microscopy and surface etching and to realize particle trapping. This paper focuses on the shift of the SPP interference patterns in the symmetric arc slit structures. The excitation models with one incident beam and two incident beams are established and analyzed respectively, and methods to shift the SPP interference patterns via adjusting the tilt angle and initial phase of the excitation beams are compared. The FDTD simulation results show that these methods can precisely shift the SPP interference patterns in the symmetrical arc slits. Compared to the linear slits, the SPP waves arising from arc slits are more strongly focused, resulting in a stronger gradient force. The characteristics of stronger focus and dynamic shifting of the focal spot give the symmetric arc slit structure unique advantages in the capture and transfer of the Rayleigh metallic particle.
For decades, accelerating beams have attracted considerable interest in fundamental physics and in various emerging applications. However, not only are conventional accelerating beam generators (such as spatial light modulators) bulky and diffraction‐inefficient, they also have a poorly resolved ability of phase manipulation that limits the accelerating beam's minimum size and maximum degree of curvature. In this study, a dielectric metasurface is used to generate highly focused nondiffractive Bessel‐like accelerating beams with predefined arbitrary trajectories within a broadband spectral range of 550–710 nm. In particular, a similar metasurface with a combined phase profile allows the generation of a Bessel‐like vortex beam with an ultrahigh numerical aperture of 0.79, resulting in a subwavelength beamwidth of 234 nm (≈0.43λ) down to the diffraction limit. In addition, various accelerating Bessel‐like beams and beam arrays with different predefined trajectories and characteristic beam parameters that are not otherwise achievable with conventional spatial light modulators are demonstrated with synthetic‐phase metasurfaces. This study promotes the diversity of Bessel‐like accelerating beams for practical applications in fields such as optical manipulation, optical storage, biomedical imaging, and material processing.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.