Article
Nanoscience & Nanotechnology
Yong Zhang, Yu He, Hongwei Wang, Lu Sun, Yikai Su
Summary: In this paper, an on-chip Luneburg lens is successfully implemented through the integration of gradient metamaterial structures and silicon waveguides, using the filling ratio mapping of silicon nanorods to achieve the gradient index distribution. A general and scalable approach for a mode size converter is demonstrated, benefiting from the aberration-free property. The silicon mode size converter exhibits the largest bandwidth, with a simulated bandwidth of 740 nm and a measured bandwidth of 220 nm.
Article
Materials Science, Multidisciplinary
Quan Yue, Eric Akmansoy
Summary: We have designed a photonic crystal flat lens with negative index for silicon photonics. The lens can focus an incident plane wave and collimate a point source wave. It operates in the first and second bands of photonic crystals and can be fabricated using silicon-on-insulator CMOS technology.
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
(2022)
Article
Optics
Hongda Lu, Zhipeng Liu, Yanbo Zhang, Ke Pang, Yong Liu
Summary: This paper introduces a novel two-dimensional partial Maxwell fish-eye (PMFE) lens with wide-angle beam scanning capability, inspired by the Gutman lens and Eaton lens. The PMFE lens demonstrates potential for wide-angle beam scanning and is experimentally verified. Measured results show wide-angle scanning ranges and low reflections and couplings.
Article
Multidisciplinary Sciences
Dmytro Vovchuk, Mykola Khobzei, Dmitry Filonov, Pavel Ginzburg
Summary: Direction of arrival (DoA) estimation is crucial in wireless applications. This paper introduces a low-cost DoA device based on a Fresnel zone plate lens, aperture, and a light-emitting diode indicator, which achieves high resolution and accuracy in DoA visualization. It can be used for adjusting communication links and identifying sources of radio wave pollution.
SCIENTIFIC REPORTS
(2022)
Article
Multidisciplinary Sciences
Fatemeh Sadeghikia, Kazem Zafari, Mohammad-Reza Dorbin, Mohamed Himdi, Ali Karami Horestani
Summary: This article focuses on the application of plasma technology to develop microwave lens antennas with controllable radiation gain. The design of a biconcave lens based on plasma dielectric material is presented, along with the procedure and electrical characteristics of a plasma lens antenna with a pyramidal horn feed. The experimental results validate the design procedure and confirm that adjusting the plasma frequency can dynamically control the radiation gain of the lens antenna.
SCIENTIFIC REPORTS
(2023)
Article
Multidisciplinary Sciences
Jose-Manuel Poyanco, Francisco Pizarro, Eva Rajo-Iglesias
Summary: This article presents a fully 3D-printed dielectric planar lens operating in the entire Ka-band. The lens is manufactured using additive manufacturing and a low-cost 3D-printer, and consists of concentric rings made of low-loss ABS filaments with high permittivity values. By adjusting the infill percentages, the desired refractive indexes are achieved. The lens incorporates a 3D-printed matching layer to reduce reflections. Simulation and measurement results show excellent agreement, confirming the feasibility of cost-effective broadband and planar lens solutions for millimeter wave bands.
SCIENTIFIC REPORTS
(2022)
Article
Optics
Yixuan Gao, Wen Xiao, Pengfei Zhao, Xiaoting Wu, Huanyang Chen
Summary: We demonstrate a device called 540-degree deflecting lens, which has a symmetric refractive index and can deflect parallel beam by 540 degrees. The expression of its gradient refractive index is obtained and generalized. It is an optical absolute instrument with self-imaging characteristic. Ray tracing and wave simulations are used to demonstrate its characteristics. Our study expands the family of absolute instruments and provides new ideas for designing optical systems.
Article
Physics, Applied
Chunyao Lu, Run Yu, Qiujun Ma, Kangyu Wang, Jing Wang, Dawei Wu
Summary: This study presents a 3D-printed mesoscale acoustic generalized Luneburg lens based on cylindrical metamaterial, demonstrating advantages such as super long work distance, no obvious sidelobe, and better acoustic impedance matching compared to isotropic lenses. The ray tracing method is used to interpret the ultra-long acoustic jets mechanism, and adjustment of lattice unit composition allows for manipulation of air and underwater acoustic waves. This work inspires a straightforward strategy for ultra-long acoustic jets with potential applications in imaging and treatment in biological tissues.
APPLIED PHYSICS LETTERS
(2021)
Article
Acoustics
Rafael Fuentes-Dominguez, Mengting Yao, Andrea Colombi, Paul Dryburgh, Don Pieris, Alexander Jackson-Crisp, Daniel Colquitt, Adam Clare, Richard J. Smith, Matt Clark
Summary: In this study, additive manufacturing was used to create a graded index metasurface for surface acoustic waves on an aluminium slab, simulating the functionality of a Luneburg lens to focus plane SAWs. The lens design was validated to only work within a narrow band, and comparison between ray analysis and experimental results indicated potential for acoustic shielding near the acoustic bandgaps.
Article
Optics
Wenyi Shao, Qiang Chen
Summary: This study investigates the performance of an all-dielectric planar Mikaelian lens for 1-D beam-steering application using ray transfer matrices and full-wave analysis. A lens prototype was fabricated and tested, showing switched-beam coverage and beam-steering capabilities. The intrinsic flat shape characteristic of this lens concept makes it a potential alternative for low-cost, low-profile, easy-to-fabricate beam-switching array antennas for microwave communication applications.
Article
Engineering, Mechanical
Liuxian Zhao, Changquan Lai, Miao Yu
Summary: This paper proposes a novel gradient index (GRIN) structural lens based on the concept of generalized Luneburg lens (GLL). The lens achieves ultralong focusing by realizing double foci and localization of energy flow between the two focal spots. The lens consists of two concentric circular regions with varying thickness and refractive indices, which can be tailored for different applications.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2023)
Review
Nanoscience & Nanotechnology
Thomas Ferreira de Lima, Eli A. Doris, Simon Bilodeau, Weipeng Zhang, Aashu Jha, Hsuan-Tung Peng, Eric C. Blow, Chaoran Huang, Alexander N. Tait, Bhavin J. Shastri, Paul R. Prucnal
Summary: This paper introduces neuromorphic photonic processors based on resonator weight banks, which are emerging candidate technology for enabling modern artificial intelligence in high speed analog systems. These purpose-built analog devices leverage the physics of resonator devices to implement vector multiplications, offering efficiency, latency, and throughput advantages over equivalent electronic circuits. However, the challenges of compensation for fabrication variations and environmental disturbances need to be addressed through automated design and control methodologies for practical deployment.
Article
Optics
Yingjie Liu, You Wu, Jiefeng Xu, Shumin Xiao, Qinghai Song, Ke Xu
Summary: This study proposes a free-form functional microheater with topology design to manipulate the refractive index distribution, enabling flexible optical wavefront shaping. Wide range of dynamic focusing and beam steering are demonstrated with a tunable meta-lens on a silicon photonic platform. The proposed tunable meta-lenses have fast thermal-optic response time and low on-chip loss, offering versatility for various on-chip meta-systems.
LASER & PHOTONICS REVIEWS
(2023)
Review
Chemistry, Multidisciplinary
Jingya Xie, Wangcheng Ye, Linjie Zhou, Xuguang Guo, Xiaofei Zang, Lin Chen, Yiming Zhu
Summary: In the past few decades, terahertz (THz) technologies have been greatly enhanced and investigated due to possible opportunities in various applications. Photonics plays a key role in the generation, modulation, and detection of THz waves, while researchers are exploring ways to use silicon photonics for THz applications. Challenges remain in high-quality hybrid silicon lasers, conversion efficiency, device integration, and fabrication for THz integrated systems.
Article
Physics, Applied
Shuaishuai Tong, Chunyu Ren, Jun Tao, Lixun Jiang
Summary: This paper presents a method for designing, realizing, and measuring a flattened focal surface underwater acoustic Luneburg lens. The lens is designed using the quasi-conformal transformation technique and constructed with metamaterials based on air-filled photosensitive resin. Numerical simulations and experimental studies demonstrate that the flattened lens has excellent focusing performance over a broad frequency band and can potentially be applied in biomedical imaging, underwater acoustic sensing, and communication.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Thales V. A. G. de Oliveira, Tobias Noerenberg, Gonzalo Alvarez-Perez, Lukas Wehmeier, Javier Taboada-Gutierrez, Maximilian Obst, Franz Hempel, Eduardo J. H. Lee, J. Michael Klopf, Ion Errea, Alexey Y. Nikitin, Susanne C. Kehr, Pablo Alonso-Gonzalez, Lukas M. Eng
Summary: Research demonstrates nanoscale-confined phonon polaritons at THz frequencies in vdW semiconductors using scattering-type scanning near-field optical microscopy and a free-electron laser, achieving extreme field confinement and low optical losses.
ADVANCED MATERIALS
(2021)
Article
Optics
Tobias Noerenberg, Lukas Wehmeier, Denny Lang, Susanne C. Kehr, Lukas M. Eng
Summary: Nanotechnology and modern materials science require reliable local probing techniques at the nanoscale. Different scanning probe microscopy methods, including scattering scanning near-field optical microscopy (s-SNOM) and Kelvin-probe force microscopy (KPFM), can be combined to compensate for undesirable electrostatic interactions and enable in situ probing of local electric potentials on sample surfaces.
Article
Multidisciplinary Sciences
Flavio H. Feres, Rafael A. Mayer, Lukas Wehmeier, Francisco C. B. Maia, E. R. Viana, Angelo Malachias, Hans A. Bechtel, J. Michael Klopf, Lukas M. Eng, Susanne C. Kehr, J. C. Gonzalez, Raul O. Freitas, Ingrid D. Barcelos
Summary: This study introduces tin oxide nanobelts as a platform for transporting phonon polaritons in the far-infrared range, showcasing their unique photonic properties and potential applications.
NATURE COMMUNICATIONS
(2021)
Article
Nanoscience & Nanotechnology
Vera M. Titze, Soraya Caixeiro, Andrea Di Falco, Marcel Schubert, Malte C. Gather
Summary: This study reports a new type of biocompatible microdisk lasers made from specific semiconductor alloy structures that can operate at red-shifted excitation and emission wavelengths. The lasers show stable performance and can be operated under both direct excitation and two-photon excitation. They also maintain stability under cell culturing conditions. With their optimized spectral characteristics and low threshold, these microlasers are ideal for cell tagging and in vivo sensing applications.
Article
Optics
Libin Yan, Jianling Xiao, Tomasz Plaskocinski, Mohammad Biabanifard, Saydulla Persheyev, Meisam Askari, Andrea Di Falco
Summary: In this study, we demonstrate the two-tier manipulation of holographic information using frequency-selective metasurfaces. The results show that these devices efficiently diffract light at designed frequency and environmental conditions, enabling the production of two different holographic images by changing the frequency and refractive index of the surrounding environment. These environmental dependent, frequency-selective metasurfaces are expected to have practical applications in holographic encryption and sensing.
Article
Optics
M. Chen, T. V. A. G. de Oliveira, I. Ilyakov, T. Noerenberg, F. Kuschewski, J-C Deinert, N. Awari, A. Ponomaryov, M. Kuntzsch, S. C. Kehr, L. M. Eng, M. Gensch, S. Kovalev
Summary: This article presents a conceptually new approach to synchronizing accelerator-based light sources and external laser systems. The method utilizes an intense accelerator-based single-cycle terahertz pulse to slice a femtosecond-level part of a longer picosecond laser pulse, achieving precise synchronization of approximately 10 fs for real-time lock-in amplifier signal demodulation. The concept was successfully demonstrated in three benchmark experiments using a 4th generation accelerator-based terahertz light source.
Article
Materials Science, Multidisciplinary
Laura C. Wynne, Cissy Zhang, Usenobong Akpan, Andrea DI Falco, Sebastian A. Schulz
Summary: This article demonstrates that enhanced light coupling into an ENZ metamaterial stack can be achieved through the design and fabrication of anti-reflection coatings, resulting in increased transmission and decreased reflection.
OPTICAL MATERIALS EXPRESS
(2022)
Article
Chemistry, Multidisciplinary
Tobias Norenberg, Gonzalo Alvarez-Perez, Maximilian Obst, Lukas Wehmeier, Franz Hempel, J. Michael Klopf, Alexey Y. Nikitin, Susanne C. Kehr, Lukas M. Eng, Pablo Alonso-Gonzalez, Thales V. A. G. de Oliveira
Summary: This study provides a thorough characterization of different hyperbolic and elliptical PhP modes in alpha-germanium(II) sulfide (GeS) using THz nanospectroscopy and theoretical analysis.
Article
Materials Science, Multidisciplinary
Jianling Xiao, Robert I. Hunter, Duncan A. Robertson, Graham M. Smith, Simon Horsley, Sebastian A. Schulz, Andrea Di Falco
Summary: This paper reports the design, fabrication, and experimental demonstration of conformable holographic metasurfaces. It is demonstrated that the holographic image produced changes when the metasurface is applied to targets with different shapes. The demonstration is based on a reflective-type metasurface with perpendicular reflected polarization to the incident light. Additionally, the parameters of the metasurface and their influence on the image quality and ability to produce independent images are critically discussed.
ADVANCED MATERIALS TECHNOLOGIES
(2023)
Article
Chemistry, Multidisciplinary
Flavio H. Feres, Ingrid D. Barcelos, Alisson R. Cadore, Lukas Wehmeier, Tobias Noerenberg, Rafael A. Mayer, Raul O. Freitas, Lukas M. Eng, Susanne C. Kehr, Francisco C. B. Maia
Summary: In this study, we used a highly brilliant and tunable free-electron laser to illuminate a nanoscope and observe the graphene nano-optical response from 1.5 to 6.0 THz. At frequencies below 2 THz, graphene exhibited a metal-like behavior and screened optical fields similar to noble metals. At 3.8 THz, plasmonic resonances caused a field-enhancement effect that improved the imaging power of graphene. Furthermore, we demonstrated tunability of the metallic behavior and the field-enhancement effect through electrical doping, providing additional control over graphene's nano-optical properties in the THz gap.
Article
Nanoscience & Nanotechnology
Jianling Xiao, Tomasz Plaskocinski, Mohammad Biabanifard, Saydulla Persheyev, Andrea Di Falco
Summary: Photonic metasurfaces provide an alternative method for optical trapping of small particles in an integrated platform. In this study, we designed and fabricated metasurfaces with a high numerical aperture of 1.2, achieving trapping stiffness greater than 400 pN/μm/W. Our results demonstrate that these metasurfaces perform comparably to microscope objectives with the same numerical aperture. We also analyzed the impact of metasurface dimension on trapping performance, showing efficient trapping with metasurfaces as small as 0.001 mm². Furthermore, we showcased the versatility of the platform by designing metasurfaces capable of creating multisite optical tweezers for extended objects.
Article
Physics, Applied
T. Plaskocinski, Y. Arita, G. D. Bruce, S. Persheyev, K. Dholakia, A. Di Falco, H. Ohadi
Summary: On-chip optical trapping systems with high scalability and low barrier to access are achieved through the fabrication of micrometer-sized parabolic mirrors. These mirrors, fabricated using CO2 laser ablation and gold deposition, enable three-dimensional optical trapping and rotation of microbeads and vaterite particles. The method allows for rapid fabrication of dense and customizable optical arrays.
APPLIED PHYSICS LETTERS
(2023)
Article
Multidisciplinary Sciences
Joseph Matson, Soeren Wasserroth, Xiang Ni, Maximilian Obst, Katja Diaz-Granados, Giulia Carini, Enrico Maria Renzi, Emanuele Galiffi, Thomas G. Folland, Lukas M. Eng, J. Michael Klopf, Stefan Mastel, Sean Armster, Vincent Gambin, Martin Wolf, Susanne C. Kehr, Andrea Alu, Alexander Paarmann, Joshua D. Caldwell
Summary: The properties of phonon polaritons (PhPs) in the monoclinic crystal ss-Ga2O3 (bGO) were investigated, and strongly asymmetric propagation and frequency dispersive optical axis were observed. The symmetry-broken propagation of hyperbolic shear polaritons in bGO was directly imaged using scanning near-field optical microscopy (sSNOM). The control and enhancement of shear-induced propagation asymmetry were demonstrated by varying the incident laser orientation and polariton momentum using different sizes of nano-antennas, and significant rotation of the hyperbola axis was observed by changing the frequency of incident light. These findings lay the groundwork for the widespread utilization and implementation of polaritons in low-symmetry crystals.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Felix G. Kaps, Susanne C. Kehr, Lukas M. Eng
Summary: This paper theoretically and experimentally explores the influence of linear polarization control on near-field coupling, demonstrating that resonantly excited samples respond with a strong near-field signal to different linear polarization angles. By varying the illumination polarization angle, the scattered near-field signatures at different wavelengths can be quantitatively compared.
APPLIED SCIENCES-BASEL
(2023)
Article
Nanoscience & Nanotechnology
Andrea Fratalocchi, Adam Fleming, Claudio Conti, Andrea Di Falco
Summary: The research presents a two-step PUF generation strategy based on deep learning, creating reliable keys verified against NIST standards. This strategy can be generalized to any PUF based on either optical or electronic implementations, assisting in the design of robust PUFs for secure authentications and encrypted communications.
