Journals > > Topics > Nanophotonics, Metamaterials, and Plasmonics
Nanophotonics, Metamaterials, and Plasmonics|51 Article(s)
Tunable hexagonal boron nitride topological optical delay line in the visible region
Hongming Fei, Min Wu, Han Lin, Yibiao Yang, and Liantuan Xiao
Tunability, ultracompact design, high group index, low loss, and broad bandwidth are desired properties for integrated optical delay lines (ODLs). However, those properties are challenging to achieve simultaneously in the visible region. This paper proposes a tunable hexagonal boron nitride topological optical delay line (ODL) in the visible region based on valley photonic crystals. The topological edge state from the beard-type boundary allows the achievement of an ultralow group velocity close to zero, which results in a large group index of 629 at 645 nm. Moreover, we demonstrate tuning of the slow-light wavelength and optical delay times with electrically tunable liquid crystals by applying external voltage. The device has an ultracompact size of 5 µm × 2.7 µm with an optical delay distance of 25a (a is the lattice constant) and a delay time of 12 ps. Our design can provide a new possibility for designing ODLs working in the visible region for optical communication and quantum computing systems. Tunability, ultracompact design, high group index, low loss, and broad bandwidth are desired properties for integrated optical delay lines (ODLs). However, those properties are challenging to achieve simultaneously in the visible region. This paper proposes a tunable hexagonal boron nitride topological optical delay line (ODL) in the visible region based on valley photonic crystals. The topological edge state from the beard-type boundary allows the achievement of an ultralow group velocity close to zero, which results in a large group index of 629 at 645 nm. Moreover, we demonstrate tuning of the slow-light wavelength and optical delay times with electrically tunable liquid crystals by applying external voltage. The device has an ultracompact size of 5 µm × 2.7 µm with an optical delay distance of 25a (a is the lattice constant) and a delay time of 12 ps. Our design can provide a new possibility for designing ODLs working in the visible region for optical communication and quantum computing systems.
Chinese Optics Letters
- Publication Date: May. 17, 2024
- Vol. 22, Issue 5, 053602 (2024)
Metalens with tilted structures for high-efficiency focusing at large-angle incidences
Yue Wang, Chen Chen, Shengjie Wu, Xin Ye, Shining Zhu, and Tao Li
The metalens has attracted remarkable attention due to its ultra-thin and ultra-light characteristics, which indicate great potential for compact imaging. However, the limited efficiency at a large angle incidence severely hinders the application of wide-angle focusing and imaging, which is pursued in the fast-developing imaging systems. Therefore, new strategies to improve the lens performance at large incident angles are in demand. In this work, we propose tilted structures for large-angle focusing with improved efficiency. Metalenses based on dynamic phase and geometric phase are designed and systematically characterized by numerical simulations. We show that tilted structures of unit cells significantly improve the lens performance at oblique incidences. In detail, the focusing efficiency of the metalens with tilted structures is increased over 25% at 30° incidence, as well as the modulation transfer function. In addition, we develop a hybrid metalens array achieving highly efficient wide-angle imaging up to 120°. We believe this design provides a feasible route toward wide-field and high-performance imaging applications. The metalens has attracted remarkable attention due to its ultra-thin and ultra-light characteristics, which indicate great potential for compact imaging. However, the limited efficiency at a large angle incidence severely hinders the application of wide-angle focusing and imaging, which is pursued in the fast-developing imaging systems. Therefore, new strategies to improve the lens performance at large incident angles are in demand. In this work, we propose tilted structures for large-angle focusing with improved efficiency. Metalenses based on dynamic phase and geometric phase are designed and systematically characterized by numerical simulations. We show that tilted structures of unit cells significantly improve the lens performance at oblique incidences. In detail, the focusing efficiency of the metalens with tilted structures is increased over 25% at 30° incidence, as well as the modulation transfer function. In addition, we develop a hybrid metalens array achieving highly efficient wide-angle imaging up to 120°. We believe this design provides a feasible route toward wide-field and high-performance imaging applications.
Chinese Optics Letters
- Publication Date: May. 14, 2024
- Vol. 22, Issue 5, 053601 (2024)
Active metasurface via magnetic control for tri-channel polarization multiplexing holography|Editors' Pick
Yu Bi, Lingling Huang, Tuo Li, Changhong Wang, Xiaofeng Zou, Lang Zhou, and Guoguo Kang
Active metasurfaces have recently attracted more attention since they can make the light manipulation be versatile and real-time. Metasurfaces-based holography possesses the advantages of high spatial resolution and enormous information capacity for applications in optical displays and encryption. In this work, a tunable polarization multiplexing holographic metasurface controlled by an external magnetic field is proposed. The elaborately designed nanoantennas are arranged on the magneto-optical intermediate layer, which is placed on the metallic reflecting layer. Since the non-diagonal elements of the dielectric tensor of the magneto-optical material become non-zero values once the external magnetic field is applied, the differential absorption for the left and right circularly polarized light can be generated. Meanwhile, the amplitude and phase can be flexibly modulated by changing the sizes of the nanoantennas. Based on this, the dynamic multichannel holographic display of metasurface in the linear and circular polarization channels is realized via magnetic control, and it can provide enhanced security for optical information storage. This work paves the way for the realization of magnetically controllable phase modulation, which is promising in dynamic wavefront control and optical information encryption. Active metasurfaces have recently attracted more attention since they can make the light manipulation be versatile and real-time. Metasurfaces-based holography possesses the advantages of high spatial resolution and enormous information capacity for applications in optical displays and encryption. In this work, a tunable polarization multiplexing holographic metasurface controlled by an external magnetic field is proposed. The elaborately designed nanoantennas are arranged on the magneto-optical intermediate layer, which is placed on the metallic reflecting layer. Since the non-diagonal elements of the dielectric tensor of the magneto-optical material become non-zero values once the external magnetic field is applied, the differential absorption for the left and right circularly polarized light can be generated. Meanwhile, the amplitude and phase can be flexibly modulated by changing the sizes of the nanoantennas. Based on this, the dynamic multichannel holographic display of metasurface in the linear and circular polarization channels is realized via magnetic control, and it can provide enhanced security for optical information storage. This work paves the way for the realization of magnetically controllable phase modulation, which is promising in dynamic wavefront control and optical information encryption.
Chinese Optics Letters
- Publication Date: Apr. 18, 2024
- Vol. 22, Issue 4, 043601 (2024)
Recent progress in thin-film lithium niobate photonic crystal [Invited]|Editors' Pick
Rui Ge, Jiangwei Wu, Xiangmin Liu, Yuping Chen, and Xianfeng Chen
Lithium niobate is a material that exhibits outstanding electro-optic, nonlinear optical, acousto-optic, piezoelectric, photorefractive, and pyroelectric properties. A thin-film lithium niobate photonic crystal can confine light in the sub-wavelength scale, which is beneficial to the integration of the lithium niobate on-chip device. The commercialization of the lithium niobate on insulator gives birth to the emergence of high-quality lithium niobate photonic crystals. In order to provide guidance to the research of lithium niobate photonic crystal devices, recent progress about fabrication, characterization, and applications of the thin-film lithium niobate photonic crystal is reviewed. The performance parameters of the different devices are compared. Lithium niobate is a material that exhibits outstanding electro-optic, nonlinear optical, acousto-optic, piezoelectric, photorefractive, and pyroelectric properties. A thin-film lithium niobate photonic crystal can confine light in the sub-wavelength scale, which is beneficial to the integration of the lithium niobate on-chip device. The commercialization of the lithium niobate on insulator gives birth to the emergence of high-quality lithium niobate photonic crystals. In order to provide guidance to the research of lithium niobate photonic crystal devices, recent progress about fabrication, characterization, and applications of the thin-film lithium niobate photonic crystal is reviewed. The performance parameters of the different devices are compared.
Chinese Optics Letters
- Publication Date: Feb. 20, 2024
- Vol. 22, Issue 3, 033602 (2024)
Vortex localization and OAM selective conversion via cylindrical metagratings
Zhanlei Hao, Shan Zhu, Cheng-Wei Qiu, Yadong Xu, and Huanyang Chen
Vortex waves with orbital angular momentum (OAM) are a highly active research topic in various fields. In this paper, we design and investigate cylindrical metagratings (CMs) with an even number of unit cells that can efficiently achieve vortex localization and specific OAM selective conversion. The multifunctional manipulation of vortex waves and the new OAM conservation law have further been confirmed through analytical calculations and numerical simulations. In addition, we qualitatively and quantitatively determine the OAM range for vortex localization and the OAM value of vortex selective conversion and also explore the stability for performance and potential applications of the designed structure. This work holds potential applications in particle manipulation and optical communication. Vortex waves with orbital angular momentum (OAM) are a highly active research topic in various fields. In this paper, we design and investigate cylindrical metagratings (CMs) with an even number of unit cells that can efficiently achieve vortex localization and specific OAM selective conversion. The multifunctional manipulation of vortex waves and the new OAM conservation law have further been confirmed through analytical calculations and numerical simulations. In addition, we qualitatively and quantitatively determine the OAM range for vortex localization and the OAM value of vortex selective conversion and also explore the stability for performance and potential applications of the designed structure. This work holds potential applications in particle manipulation and optical communication.
Chinese Optics Letters
- Publication Date: Mar. 04, 2024
- Vol. 22, Issue 3, 033601 (2024)
A vectorial model for the nonlinear gradient force exerted on metallic Rayleigh nanoparticles
Zheng Zhu, Yuquan Zhang, Changjun Min, Aurèle J. L. Adam, H. Paul Urbach, and Xiaocong Yuan
Optical tweezers have proved to be a powerful tool with a wide range of applications. The gradient force plays a vital role in the stable optical trapping of nano-objects. The scalar method is convenient and effective for analyzing the gradient force in traditional optical trapping. However, when the third-order nonlinear effect of the nano-object is stimulated, the scalar method cannot adequately present the optical response of the metal nanoparticle to the external optical field. Here, we propose a theoretical model to interpret the nonlinear gradient force using the vector method. By combining the optical Kerr effect, the polarizability vector of the metallic nanoparticle is derived. A quantitative analysis is obtained for the gradient force as well as for the optical potential well. The vector method yields better agreement with reported experimental observations. We suggest that this method could lead to a deeper understanding of the physics relevant to nonlinear optical trapping and binding phenomena. Optical tweezers have proved to be a powerful tool with a wide range of applications. The gradient force plays a vital role in the stable optical trapping of nano-objects. The scalar method is convenient and effective for analyzing the gradient force in traditional optical trapping. However, when the third-order nonlinear effect of the nano-object is stimulated, the scalar method cannot adequately present the optical response of the metal nanoparticle to the external optical field. Here, we propose a theoretical model to interpret the nonlinear gradient force using the vector method. By combining the optical Kerr effect, the polarizability vector of the metallic nanoparticle is derived. A quantitative analysis is obtained for the gradient force as well as for the optical potential well. The vector method yields better agreement with reported experimental observations. We suggest that this method could lead to a deeper understanding of the physics relevant to nonlinear optical trapping and binding phenomena.
Chinese Optics Letters
- Publication Date: Feb. 27, 2024
- Vol. 22, Issue 2, 023603 (2024)
Dual-symmetry-perturbed all-dielectric resonant metasurfaces for high-Q perfect light absorption
Junyang Ge, Yixiao Gao, Lei Xu, Ning Zhou, and Xiang Shen
We demonstrate a high-Q perfect light absorber based on all-dielectric doubly-resonant metasurface. Leveraging bound states in the continuum (BICs) protected by different symmetries, we manage to independently manipulate the Q factors of the two degenerate quasi-BICs through dual-symmetry perturbations, achieving precise matching of the radiative and nonradiative Q factors for degenerate critical coupling. We achieve a narrowband light absorption with a >600 Q factor and a > 99% absorptance at λ0 = 1550 nm on an asymmetric germanium metasurface with a 0.2λ0 thickness. Our work provides a new strategy for engineering multiresonant metasurfaces for narrowband light absorption and nonlinear applications. We demonstrate a high-Q perfect light absorber based on all-dielectric doubly-resonant metasurface. Leveraging bound states in the continuum (BICs) protected by different symmetries, we manage to independently manipulate the Q factors of the two degenerate quasi-BICs through dual-symmetry perturbations, achieving precise matching of the radiative and nonradiative Q factors for degenerate critical coupling. We achieve a narrowband light absorption with a >600 Q factor and a > 99% absorptance at λ0 = 1550 nm on an asymmetric germanium metasurface with a 0.2λ0 thickness. Our work provides a new strategy for engineering multiresonant metasurfaces for narrowband light absorption and nonlinear applications.
Chinese Optics Letters
- Publication Date: Feb. 27, 2024
- Vol. 22, Issue 2, 023602 (2024)
Inverse-designed Jones matrix metasurfaces for high-performance meta-polarizers
Zhi-Qiang Wang, Feng-Jun Li, Qian-Mei Deng, Zhou Wan, Xiangping Li, and Zi-Lan Deng
Polarizers have always been an important optical component for optical engineering and have played an indispensable part of polarization imaging systems. Metasurface polarizers provide an excellent platform to achieve miniaturization, high resolution, and low cost of polarization imaging systems. Here, we proposed freeform metasurface polarizers derived by adjoint-based inverse design of a full-Jones matrix with gradient-descent optimization. We designed multiple freeform polarizers with different filtered states of polarization (SOPs), including circular polarizers, elliptical polarizers, and linear polarizers that could cover the full Poincaré sphere. Note that near-unitary polarization dichroism and the ultrahigh polarization extinction ratio (ER) reaching 50 dB were achieved for optimized circular polarizers. The multiple freeform polarizers with filtered polarization state locating at four vertices of an inscribed regular tetrahedron of the Poincaré sphere are designed to form a full-Stokes parameters micropolarizer array. Our work provides a novel approach, we believe, for the design of meta-polarizers that may have potential applications in polarization imaging, polarization detection, and communication. Polarizers have always been an important optical component for optical engineering and have played an indispensable part of polarization imaging systems. Metasurface polarizers provide an excellent platform to achieve miniaturization, high resolution, and low cost of polarization imaging systems. Here, we proposed freeform metasurface polarizers derived by adjoint-based inverse design of a full-Jones matrix with gradient-descent optimization. We designed multiple freeform polarizers with different filtered states of polarization (SOPs), including circular polarizers, elliptical polarizers, and linear polarizers that could cover the full Poincaré sphere. Note that near-unitary polarization dichroism and the ultrahigh polarization extinction ratio (ER) reaching 50 dB were achieved for optimized circular polarizers. The multiple freeform polarizers with filtered polarization state locating at four vertices of an inscribed regular tetrahedron of the Poincaré sphere are designed to form a full-Stokes parameters micropolarizer array. Our work provides a novel approach, we believe, for the design of meta-polarizers that may have potential applications in polarization imaging, polarization detection, and communication.
Chinese Optics Letters
- Publication Date: Feb. 27, 2024
- Vol. 22, Issue 2, 023601 (2024)
Four-channel metasurface for multiplexing images under two nonorthogonal polarization states
Wenyuan Liu, Yizhou Zhuo, Likun Xiao, Chen Chen, Shu Shang, Hongzhan Liu, Hongyun Meng, Faqiang Wang, Xiangbo Yang, and Zhongchao Wei
By its unparalleled capacity to manipulate optical parameters, metasurfaces demonstrate the ability to simultaneously manipulate the amplitude and phase of incident light. Exhibiting both near-field nanoprinting images and far-field holography images is a quintessential illustration of this capability. In preceding investigations, image multiplexing commonly transpires within the single polarization state or orthogonal polarization states, thereby exhibiting a deficiency in terms of information security when contrasted with the nonorthogonal polarization states. In this research, a multifunctional metasurface with the capability of exhibiting four-channel images has been proposed by using a nanobrick as a quarter-wave plate. Through the adjustment of the orientation angles of each nanobrick, nanoprinting can be displayed under both linearly and circularly polarized light. Building on this, the propagation phase is combined with the geometric phase to generate diverse phase delays, enabling the metasurface to be multiplexed under two nonorthogonal polarization states to achieve four-channel image displays. Intriguingly, bidirectional nanoprinting and bidirectional holography can be achieved by altering the direction of incidence polarization states. The proposed metasurface platform can open new possibilities for creating compact multifunctional optical devices, while also enhancing applications in multichannel image displays, information anticounterfeiting, and encryption. By its unparalleled capacity to manipulate optical parameters, metasurfaces demonstrate the ability to simultaneously manipulate the amplitude and phase of incident light. Exhibiting both near-field nanoprinting images and far-field holography images is a quintessential illustration of this capability. In preceding investigations, image multiplexing commonly transpires within the single polarization state or orthogonal polarization states, thereby exhibiting a deficiency in terms of information security when contrasted with the nonorthogonal polarization states. In this research, a multifunctional metasurface with the capability of exhibiting four-channel images has been proposed by using a nanobrick as a quarter-wave plate. Through the adjustment of the orientation angles of each nanobrick, nanoprinting can be displayed under both linearly and circularly polarized light. Building on this, the propagation phase is combined with the geometric phase to generate diverse phase delays, enabling the metasurface to be multiplexed under two nonorthogonal polarization states to achieve four-channel image displays. Intriguingly, bidirectional nanoprinting and bidirectional holography can be achieved by altering the direction of incidence polarization states. The proposed metasurface platform can open new possibilities for creating compact multifunctional optical devices, while also enhancing applications in multichannel image displays, information anticounterfeiting, and encryption.
Chinese Optics Letters
- Publication Date: Aug. 21, 2023
- Vol. 21, Issue 9, 093601 (2023)
Active tuning of Si metasurface with large area
Bintao Du, Zhihai Wu, Chengkun Dong, Jun Wu, and Jun Xia
All-dielectric metasurfaces are usually limited because of their static functionality and small scale. In this paper, we use an easy nanofabrication technique to fabricate all-dielectric metasurfaces with the advantages of having dynamic tunability and a large area. Using an anodized aluminum oxide (AAO) template as an evaporation mask, a large-area metasurface embedded in polydimethylsiloxane (PDMS) (>2 cm2) is fabricated. The metasurface exhibits remarkable electric dipole (ED) and magnetic dipole (MD) resonances. Based on the solvent-swelling effect of PDMS in 20% toluene, the ED/MD resonance peak shifts dynamically ∼40 nm to red. So far, to the best of our knowledge, a large-area metasurface embedded in PDMS and achieved by using the AAO template method has not appeared. All-dielectric metasurfaces are usually limited because of their static functionality and small scale. In this paper, we use an easy nanofabrication technique to fabricate all-dielectric metasurfaces with the advantages of having dynamic tunability and a large area. Using an anodized aluminum oxide (AAO) template as an evaporation mask, a large-area metasurface embedded in polydimethylsiloxane (PDMS) (>2 cm2) is fabricated. The metasurface exhibits remarkable electric dipole (ED) and magnetic dipole (MD) resonances. Based on the solvent-swelling effect of PDMS in 20% toluene, the ED/MD resonance peak shifts dynamically ∼40 nm to red. So far, to the best of our knowledge, a large-area metasurface embedded in PDMS and achieved by using the AAO template method has not appeared.
Chinese Optics Letters
- Publication Date: Jul. 12, 2023
- Vol. 21, Issue 7, 073601 (2023)
Topics
© Copyright 2018-2021 | Chinese Laser Press. All Rights Reserved 沪ICP备15018463号-20