@article{26987,
  abstract     = {{Optical metasurfaces are perfect candidates for the phase and amplitude modulation of light, featuring an excellent basis for holographic applications. In this work, we present a dual amplitude holographic scheme based on the photon sieve principle, which is then combined with a phase hologram by utilizing the Pancharatnam–Berry phase. We demonstrate that two types of apertures, rectangular and square shapes in a gold film filled with silicon nanoantennas are sufficient to create two amplitude holograms at two different wavelengths in the visible, multiplexed with an additional phase-only hologram. The nanoantennas are tailored to adjust the spectral transmittance of the apertures, enabling the wavelength sensitivity. The phase-only hologram is implemented by utilizing the anisotropic rectangular structure. Interestingly, such three holograms have quantitative mathematical correlations with each other. Thus, the flexibility of polarization and wavelength channels can be utilized with custom-tailored features to achieve such amplitude and phase holography simultaneously without sacrificing any space-bandwidth product. The present scheme has the potential to store different pieces of information which can be displayed separately by switching the wavelength or the polarization state of the reading light beam.}},
  author       = {{Frese, Daniel and Sain, Basudeb and Zhou, Hongqiang and Wang, Yongtian and Huang, Lingling and Zentgraf, Thomas}},
  issn         = {{2192-8614}},
  journal      = {{Nanophotonics}},
  number       = {{18}},
  pages        = {{4543--4550}},
  publisher    = {{De Gruyter}},
  title        = {{{A wavelength and polarization selective photon sieve for holographic applications}}},
  doi          = {{10.1515/nanoph-2021-0440}},
  volume       = {{10}},
  year         = {{2021}},
}

@article{25227,
  abstract     = {{<jats:title>Abstract</jats:title><jats:p>Quantum well (QW) heterostructures have been extensively used for the realization of a wide range of optical and electronic devices. Exploiting their potential for further improvement and development requires a fundamental understanding of their electronic structure. So far, the most commonly used experimental techniques for this purpose have been all-optical spectroscopy methods that, however, are generally averaging in momentum space. Additional information can be gained by angle-resolved photoelectron spectroscopy (ARPES), which measures the electronic structure with momentum resolution. Here we report on the use of extremely low-energy ARPES (photon energy ~ 7 eV) to increase depth sensitivity and access buried QW states, located at 3 nm and 6 nm below the surface of cubic-GaN/AlN and GaAs/AlGaAs heterostructures, respectively. We find that the QW states in cubic-GaN/AlN can indeed be observed, but not their energy dispersion, because of the high surface roughness. The GaAs/AlGaAs QW states, on the other hand, are buried too deep to be detected by extremely low-energy ARPES. Since the sample surface is much flatter, the ARPES spectra of the GaAs/AlGaAs show distinct features in momentum space, which can be reconducted to the band structure of the topmost surface layer of the QW structure. Our results provide important information about the samples’ properties required to perform extremely low-energy ARPES experiments on electronic states buried in semiconductor heterostructures.</jats:p>}},
  author       = {{Hajlaoui, Mahdi and Ponzoni, Stefano and Deppe, Michael and Henksmeier, Tobias and As, Donat Josef and Reuter, Dirk and Zentgraf, Thomas and Springholz, Gunther and Schneider, Claus Michael and Cramm, Stefan and Cinchetti, Mirko}},
  issn         = {{2045-2322}},
  journal      = {{Scientific Reports}},
  title        = {{{Extremely low-energy ARPES of quantum well states in cubic-GaN/AlN and GaAs/AlGaAs heterostructures}}},
  doi          = {{10.1038/s41598-021-98569-6}},
  volume       = {{11}},
  year         = {{2021}},
}

@article{21821,
  abstract     = {{We present a combined experimental and numerical study of the far-field emission properties of optical travelling wave antennas made from low-loss dielectric materials. The antennas considered here are composed of two simple building blocks, a director and a reflector, deposited on a glass substrate. Colloidal quantum dots placed in the feed gap between the two elements serve as internal light source. The emission profile of the antenna is mainly formed by the director while the reflector suppresses backward emission. Systematic studies of the director dimensions as well as variation of antenna material show that the effective refractive index of the director primarily governs the far-field emission pattern. Below cut off, i.e., if the director’s effective refractive index is smaller than the refractive index of the substrate, the main lobe results from leaky wave emission along the director. In contrast, if the director supports a guided mode, the emission predominately originates from the end facet of the director.}},
  author       = {{Leuteritz, T. and Farheen, Henna and Qiao, S. and Spreyer, F. and Schlickriede, Christian and Zentgraf, Thomas and Myroshnychenko, Viktor and Förstner, Jens and Linden, S.}},
  issn         = {{1094-4087}},
  journal      = {{Optics Express}},
  keywords     = {{tet_topic_opticalantenna}},
  number       = {{10}},
  title        = {{{Dielectric travelling wave antennas for directional light emission}}},
  doi          = {{10.1364/oe.422984}},
  volume       = {{29}},
  year         = {{2021}},
}

@article{21475,
  author       = {{Frese, Daniel and Wei, Qunshuo and Wang, Yongtian and Cinchetti, Mirko and Huang, Lingling and Zentgraf, Thomas}},
  issn         = {{2330-4022}},
  journal      = {{ACS Photonics}},
  number       = {{4}},
  pages        = {{1013--1019}},
  title        = {{{Nonlinear Bicolor Holography Using Plasmonic Metasurfaces}}},
  doi          = {{10.1021/acsphotonics.1c00028}},
  volume       = {{8}},
  year         = {{2021}},
}

@article{17390,
  author       = {{Chantakit, Teanchai and Schlickriede, Christian and Sain, Basudeb and Meyer, Fabian and Weiss, Thomas and Chattham, Nattaporn and Zentgraf, Thomas}},
  issn         = {{2327-9125}},
  journal      = {{Photonics Research}},
  number       = {{9}},
  pages        = {{1435--1440}},
  publisher    = {{OSA}},
  title        = {{{All-dielectric silicon metalens for two-dimensional particle manipulation in optical tweezers}}},
  doi          = {{10.1364/prj.389200}},
  volume       = {{8}},
  year         = {{2020}},
}

@article{17523,
  abstract     = {{<jats:p>Compact and robust cold atom sources are increasingly important for quantum research, especially for transferring cutting-edge quantum science into practical applications. In this study, we report on a novel scheme that uses a metasurface optical chip to replace the conventional bulky optical elements used to produce a cold atomic ensemble with a single incident laser beam, which is split by the metasurface into multiple beams of the desired polarization states. Atom numbers ~10<jats:sup>7</jats:sup> and temperatures (about 35 μK) of relevance to quantum sensing are achieved in a compact and robust fashion. Our work highlights the substantial progress toward fully integrated cold atom quantum devices by exploiting metasurface optical chips, which may have great potential in quantum sensing, quantum computing, and other areas.</jats:p>}},
  author       = {{Zhu, Lingxiao and Liu, Xuan and Sain, Basudeb and Wang, Mengyao and Schlickriede, Christian and Tang, Yutao and Deng, Junhong and Li, Kingfai and Yang, Jun and Holynski, Michael and Zhang, Shuang and Zentgraf, Thomas and Bongs, Kai and Lien, Yu-Hung and Li, Guixin}},
  issn         = {{2375-2548}},
  journal      = {{Science Advances}},
  number       = {{31}},
  publisher    = {{American Association for the Advancement of Science}},
  title        = {{{A dielectric metasurface optical chip for the generation of cold atoms}}},
  doi          = {{10.1126/sciadv.abb6667}},
  volume       = {{6}},
  year         = {{2020}},
}

@inbook{20847,
  author       = {{Zentgraf, Thomas and Chen, Shumei and Li, Guixin and Zhang, Shuang}},
  booktitle    = {{Nanoantennas and Plasmonics: Modelling, design and fabrication}},
  editor       = {{Werner, Douglas H. and Campbell, Sawyer D. and Kang, Lei}},
  publisher    = {{The Institution of Engineering and Technology}},
  title        = {{{Plasmonic metasurfaces for controlling harmonic generations}}},
  doi          = {{10.1049/SBEW540E_ch8}},
  year         = {{2020}},
}

@article{16839,
  author       = {{Sain, Basudeb and Zentgraf, Thomas}},
  issn         = {{2047-7538}},
  journal      = {{Light: Science & Applications}},
  pages        = {{67}},
  title        = {{{Metasurfaces help lasers to mode-lock}}},
  doi          = {{10.1038/s41377-020-0312-1}},
  volume       = {{9}},
  year         = {{2020}},
}

@article{16931,
  author       = {{Zhou, Hongqiang and Sain, Basudeb and Wang, Yongtian and Schlickriede, Christian and Zhao, Ruizhe and Zhang, Xue and Wei, Qunshuo and Li, Xiaowei and Huang, Lingling and Zentgraf, Thomas}},
  issn         = {{1936-0851}},
  journal      = {{ACS Nano}},
  number       = {{5}},
  pages        = {{5553–5559}},
  title        = {{{Polarization-Encrypted Orbital Angular Momentum Multiplexed Metasurface Holography}}},
  doi          = {{10.1021/acsnano.9b09814}},
  volume       = {{14}},
  year         = {{2020}},
}

@article{16944,
  author       = {{Schlickriede, Christian and Kruk, Sergey S. and Wang, Lei and Sain, Basudeb and Kivshar, Yuri and Zentgraf, Thomas}},
  issn         = {{1530-6984}},
  journal      = {{Nano Letters}},
  number       = {{6}},
  pages        = {{4370–4376}},
  title        = {{{Nonlinear imaging with all-dielectric metasurfaces}}},
  doi          = {{10.1021/acs.nanolett.0c01105}},
  volume       = {{20}},
  year         = {{2020}},
}

@article{15480,
  abstract     = {{<jats:p>The nonlinear processes of frequency conversion such as second harmonic generation (SHG) usually obey certain selection rules, resulting from the preservation of different kinds of physical quantities, e.g. the angular momentum. For the SHG created by a monolayer of transition-metal dichalcogenides (TMDCs) such as WS<jats:sub>2</jats:sub>, the valley-exciton locked selection rule predicts an SHG signal in the cross-polarization state. By combining plasmonic nanostructures with a monolayer of TMDC, a hybrid metasurface is realized, which affects this nonlinear process because of an additional polarization conversion process. Here, we observe that the plasmonic metasurface modifies the light-matter interaction with the TMDC, resulting in an SHG signal that is co-polarized with respect to the incident field, which is usually forbidden for the monolayers of TMDC. We fabricate such hybrid metasurfaces by placing plasmonic nanorods on top of a monolayer WS<jats:sub>2</jats:sub> and study the valley-exciton locked SHG emission from such system for different parameters, such as wavelength and polarization. Furthermore, we show the potential of the hybrid metasurface for tailoring nonlinear processes by adding additional phase information to the SHG signal using the Pancharatnam-Berry phase effect. This allows direct tailoring of the SHG emission to the far-field.</jats:p>}},
  author       = {{Spreyer, Florian and Zhao, Ruizhe and Huang, Lingling and Zentgraf, Thomas}},
  issn         = {{2192-8614}},
  journal      = {{Nanophotonics}},
  number       = {{2}},
  pages        = {{351–360}},
  title        = {{{Second harmonic imaging of plasmonic Pancharatnam-Berry phase metasurfaces coupled to monolayers of WS2}}},
  doi          = {{10.1515/nanoph-2019-0378}},
  volume       = {{9}},
  year         = {{2020}},
}

@article{16197,
  abstract     = {{Nonlinear Pancharatnam–Berry phase metasurfaces facilitate the nontrivial phase modulation for frequency conversion processes by leveraging photon‐spin dependent nonlinear geometric‐phases. However, plasmonic metasurfaces show some severe limitation for nonlinear frequency conversion due to the intrinsic high ohmic loss and low damage threshold of plasmonic nanostructures. Here, the nonlinear geometric‐phases associated with the third‐harmonic generation process occurring in all‐dielectric metasurfaces is studied systematically, which are composed of silicon nanofins with different in‐plane rotational symmetries. It is found that the wave coupling among different field components of the resonant fundamental field gives rise to the appearance of different nonlinear geometric‐phases of the generated third‐harmonic signals. The experimental observations of the nonlinear beam steering and nonlinear holography realized in this work by all‐dielectric geometric‐phase metasurfaces are well explained with the developed theory. This work offers a new physical picture to understand the nonlinear optical process occurring at nanoscale dielectric resonators and will help in the design of nonlinear metasurfaces with tailored phase properties.}},
  author       = {{Liu, Bingyi and Sain, Basudeb and Reineke, Bernhard and Zhao, Ruizhe and Meier, Cedrik and Huang, Lingling and Jiang, Yongyuan and Zentgraf, Thomas}},
  issn         = {{2195-1071}},
  journal      = {{Advanced Optical Materials}},
  number       = {{9}},
  publisher    = {{Wiley}},
  title        = {{{Nonlinear Wavefront Control by Geometric-Phase Dielectric Metasurfaces: Influence of Mode Field and Rotational Symmetry}}},
  doi          = {{10.1002/adom.201902050}},
  volume       = {{8}},
  year         = {{2020}},
}

@article{16301,
  author       = {{Atorf, Bernhard and Mühlenbernd, Holger and Zentgraf, Thomas and Kitzerow, Heinz-Siegfried}},
  issn         = {{1094-4087}},
  journal      = {{Optics Express}},
  number       = {{6}},
  pages        = {{8898--8908}},
  title        = {{{All-optical switching of a dye-doped liquid crystal plasmonic metasurface}}},
  doi          = {{10.1364/oe.383877}},
  volume       = {{28}},
  year         = {{2020}},
}

@article{8797,
  abstract     = {{Free from phase-matching constraints, plasmonic metasurfaces have contributed significantly to the control of optical nonlinearity and enhancement of nonlinear generation efficiency by engineering subwavelength meta-atoms. However, high dissipative losses and inevitable thermal heating limit their applicability in nonlinear nanophotonics. All-dielectric metasurfaces, supporting both electric and magnetic Mie-type resonances in their nanostructures, have appeared as a promising alternative to nonlinear plasmonics. High-index dielectric nanostructures, allowing additional magnetic resonances, can induce magnetic nonlinear effects, which, along with electric nonlinearities, increase the nonlinear conversion efficiency. In addition, low dissipative losses and high damage thresholds provide an extra degree of freedom for operating at high pump intensities, resulting in a considerable enhancement of the nonlinear processes. We discuss the current state of the art in the intensely developing area of all-dielectric nonlinear nanostructures and metasurfaces, including the role of Mie modes, Fano resonances, and anapole moments for harmonic generation, wave mixing, and ultrafast optical switching. Furthermore, we review the recent progress in the nonlinear phase and wavefront control using all-dielectric metasurfaces. We discuss techniques to realize all-dielectric metasurfaces for multifunctional applications and generation of second-order nonlinear processes from complementary metal–oxide–semiconductor-compatible materials.}},
  author       = {{Sain, Basudeb and Meier, Cedrik and Zentgraf, Thomas}},
  issn         = {{2577-5421}},
  journal      = {{Advanced Photonics}},
  number       = {{2}},
  pages        = {{024002}},
  title        = {{{Nonlinear optics in all-dielectric nanoantennas and metasurfaces: a review}}},
  doi          = {{10.1117/1.ap.1.2.024002}},
  volume       = {{1}},
  year         = {{2019}},
}

@article{9897,
  author       = {{Protte, Maximilian and Weber, Nils and Golla, Christian and Zentgraf, Thomas and Meier, Cedrik}},
  issn         = {{0021-8979}},
  journal      = {{Journal of Applied Physics}},
  title        = {{{Strong nonlinear optical response from ZnO by coupled and lattice-matched nanoantennas}}},
  doi          = {{10.1063/1.5093257}},
  volume       = {{125}},
  year         = {{2019}},
}

@article{11953,
  abstract     = {{As flexible optical devices that can manipulate the phase and amplitude of light, metasurfaces would clearly benefit from directional optical properties. However, single layer metasurface systems consisting of two-dimensional nanoparticle arrays exhibit only a weak spatial asymmetry perpendicular to the surface and therefore have mostly symmetric transmission features. Here, we present a metasurface design principle for nonreciprocal polarization encryption of holographic images. Our approach is based on a two-layer plasmonic metasurface design that introduces a local asymmetry and generates a bidirectional functionality with full phase and amplitude control of the transmitted light. The encoded hologram is designed to appear in a particular linear cross-polarization channel, while it is disappearing in the reverse propagation direction. Hence, layered metasurface systems can feature asymmetric transmission with full phase and amplitude control and therefore expand the design freedom in nanoscale optical devices toward asymmetric information processing and security features for anticounterfeiting applications.}},
  author       = {{Frese, Daniel and Wei, Qunshuo and Wang, Yongtian and Huang, Lingling and Zentgraf, Thomas}},
  issn         = {{1530-6984}},
  journal      = {{Nano Letters}},
  number       = {{6}},
  pages        = {{3976--3980}},
  title        = {{{Nonreciprocal Asymmetric Polarization Encryption by Layered Plasmonic Metasurfaces}}},
  doi          = {{10.1021/acs.nanolett.9b01298}},
  volume       = {{19}},
  year         = {{2019}},
}

@article{11955,
  author       = {{Li, Tianyou and Wei, Qunshuo and Reineke, Bernhard and Walter, Felicitas and Wang, Yongtian and Zentgraf, Thomas and Huang, Lingling}},
  issn         = {{1094-4087}},
  journal      = {{Optics Express}},
  number       = {{15}},
  pages        = {{21153--21162}},
  title        = {{{Reconfigurable metasurface hologram by utilizing addressable dynamic pixels}}},
  doi          = {{10.1364/oe.27.021153}},
  volume       = {{27}},
  year         = {{2019}},
}

@article{12917,
  author       = {{Reineke, Bernhard and Sain, Basudeb and Zhao, Ruizhe and Carletti, Luca and Liu, Bingyi and Huang, Lingling and de Angelis, Costantino and Zentgraf, Thomas}},
  issn         = {{1530-6984}},
  journal      = {{Nano Letters}},
  number       = {{9}},
  pages        = {{6585–6591}},
  title        = {{{Silicon metasurfaces for third harmonic geometric phase manipulation and multiplexed holography}}},
  doi          = {{10.1021/acs.nanolett.9b02844}},
  volume       = {{19}},
  year         = {{2019}},
}

@article{12919,
  author       = {{Georgi, Philip and Massaro, Marcello and Luo, Kai Hong and Sain, Basudeb and Montaut, Nicola and Herrmann, Harald and Weiss, Thomas and Li, Guixin and Silberhorn, Christine and Zentgraf, Thomas}},
  issn         = {{2047-7538}},
  journal      = {{Light: Science & Applications}},
  pages        = {{70}},
  title        = {{{Metasurface interferometry toward quantum sensors}}},
  doi          = {{10.1038/s41377-019-0182-6}},
  volume       = {{8}},
  year         = {{2019}},
}

@article{14870,
  author       = {{Wei, Qunshuo and Sain, Basudeb and Wang, Yongtian and Reineke, Bernhard and Li, Xiaowei and Huang, Lingling and Zentgraf, Thomas}},
  issn         = {{1530-6984}},
  journal      = {{Nano Letters}},
  number       = {{12}},
  pages        = {{8964–8971}},
  title        = {{{Simultaneous Spectral and Spatial Modulation for Color Printing and Holography Using All-dielectric Metasurfaces}}},
  doi          = {{10.1021/acs.nanolett.9b03957}},
  volume       = {{19}},
  year         = {{2019}},
}