- Special Issue
- Optical Metasurfaces: Fundamentals and Applications
- 12 Article (s)
Optical metasurfaces: fundamentals and applications
Thomas Pertsch, Shumin Xiao, Arka Majumdar, and Guixin Li
Optical metasurfaces are currently an important research area all around the world because of their wide application opportunities in imaging, wavefront engineering, nonlinear optics, quantum information processing, just to name a few. The feature issue “Optical Metasurfaces: Fundamentals and Applications” in Photonics Research allows for archival publication of the most recent works in optical metasurface and provides for broad dissemination in the photonics community. Optical metasurfaces are currently an important research area all around the world because of their wide application opportunities in imaging, wavefront engineering, nonlinear optics, quantum information processing, just to name a few. The feature issue “Optical Metasurfaces: Fundamentals and Applications” in Photonics Research allows for archival publication of the most recent works in optical metasurface and provides for broad dissemination in the photonics community.
Photonics Research
- Publication Date: Apr. 21, 2023
- Vol. 11, Issue 5, OMFA1 (2023)
Bright single-photon sources in the telecom band by deterministically coupling single quantum dots to a hybrid circular Bragg resonator
Shi-Wen Xu, Yu-Ming Wei, Rong-Bin Su, Xue-Shi Li, Pei-Nian Huang, Shun-Fa Liu, Xiao-Ying Huang, Ying Yu, Jin Liu, and Xue-Hua Wang
High-performance solid-state quantum sources in the telecom band are of paramount importance for long-distance quantum communications and the quantum Internet by taking advantage of a low-loss optical fiber network. Here, we demonstrate bright telecom-wavelength single-photon sources based on In(Ga)As/GaAs quantum dots (QDs) deterministically coupled to hybrid circular Bragg resonators (h-CBRs) by using a wide-field fluorescence imaging technique. The QD emissions are redshifted toward the telecom O-band by using an ultra-low InAs growth rate and an InGaAs strain reducing layer. Single-photon emissions under both continuous wave (CW) and pulsed operations are demonstrated, showing high brightness with count rates of 1.14 MHz and 0.34 MHz under saturation powers and single-photon purities of g(2)(0)=0.11±0.02 (CW) and g(2)(0)=0.087±0.003 (pulsed) at low excitation powers. A Purcell factor of 4.2 with a collection efficiency of 11.2%±1% at the first lens is extracted, suggesting efficient coupling between the QD and h-CBR. Our work contributes to the development of highly efficient single-photon sources in the telecom band for fiber-based quantum communication and future distributed quantum networks. High-performance solid-state quantum sources in the telecom band are of paramount importance for long-distance quantum communications and the quantum Internet by taking advantage of a low-loss optical fiber network. Here, we demonstrate bright telecom-wavelength single-photon sources based on In(Ga)As/GaAs quantum dots (QDs) deterministically coupled to hybrid circular Bragg resonators (h-CBRs) by using a wide-field fluorescence imaging technique. The QD emissions are redshifted toward the telecom O-band by using an ultra-low InAs growth rate and an InGaAs strain reducing layer. Single-photon emissions under both continuous wave (CW) and pulsed operations are demonstrated, showing high brightness with count rates of 1.14 MHz and 0.34 MHz under saturation powers and single-photon purities of g(2)(0)=0.11±0.02 (CW) and g(2)(0)=0.087±0.003 (pulsed) at low excitation powers. A Purcell factor of 4.2 with a collection efficiency of 11.2%±1% at the first lens is extracted, suggesting efficient coupling between the QD and h-CBR. Our work contributes to the development of highly efficient single-photon sources in the telecom band for fiber-based quantum communication and future distributed quantum networks.
Photonics Research
- Publication Date: Jul. 21, 2022
- Vol. 10, Issue 8, B1 (2022)
Metasurface for oscillatory spin splitting along the optical path
Yu Li, Xinhao Fan, Xuyue Guo, Yi Zhang, Sheng Liu, Bingyan Wei, Dandan Wen, Peng Li, and Jianlin Zhao
Spin splitting of light originates from the interplay between the polarization and spatial degrees of freedom as a fundamental constituent of the emerging spin photonics, providing a prominent pathway for manipulating photon spin and developing exceptional photonic devices. However, previously relevant devices were mainly designed for routing monotonous spin splitting of light. Here, we realize an oscillatory spin splitting of light via metasurface with two channel Pancharatnam–Berry phases. For the incidence of a linearly polarized light, the concomitant phases arising from opposite spin states transition within pathways of the metasurface induce lateral spin splitting of light with alternately changed transport direction during beam guiding. We demonstrate the invariance of this phenomenon with an analogous gauge transformation. This work provides a new insight on steering the photon spin and is expected to explore a novel guiding mechanism of relativistic spinning particles, as well as applications of optical trapping and chirality sorting. Spin splitting of light originates from the interplay between the polarization and spatial degrees of freedom as a fundamental constituent of the emerging spin photonics, providing a prominent pathway for manipulating photon spin and developing exceptional photonic devices. However, previously relevant devices were mainly designed for routing monotonous spin splitting of light. Here, we realize an oscillatory spin splitting of light via metasurface with two channel Pancharatnam–Berry phases. For the incidence of a linearly polarized light, the concomitant phases arising from opposite spin states transition within pathways of the metasurface induce lateral spin splitting of light with alternately changed transport direction during beam guiding. We demonstrate the invariance of this phenomenon with an analogous gauge transformation. This work provides a new insight on steering the photon spin and is expected to explore a novel guiding mechanism of relativistic spinning particles, as well as applications of optical trapping and chirality sorting.
Photonics Research
- Publication Date: Aug. 19, 2022
- Vol. 10, Issue 9, B7 (2022)
Anisotropic Fermat’s principle for controlling hyperbolic van der Waals polaritons
Sicen Tao, Tao Hou, Yali Zeng, Guangwei Hu, Zixun Ge, Junke Liao, Shan Zhu, Tan Zhang, Cheng-Wei Qiu, and Huanyang Chen
Transformation optics (TO) facilitates flexible designs of spatial modulation of optical materials via coordinate transformations, thus, enabling on-demand manipulations of electromagnetic waves. However, the application of TO theory in control of hyperbolic waves remains elusive due to the spatial metric signature transition from (+,+) to (-,+) of a two-dimensional hyperbolic geometry. Here, we proposed a distinct Pythagorean theorem, which leads to establishing an anisotropic Fermat’s principle. It helps to construct anisotropic geometries and is a powerful tool for manipulating hyperbolic waves at the nanoscale and polaritons. Making use of absolute instruments, the excellent collimating and focusing behaviors of naturally in-plane hyperbolic polaritons in van der Waals α–MoO3 layers are demonstrated, which opens up a new way for polaritons manipulation. Transformation optics (TO) facilitates flexible designs of spatial modulation of optical materials via coordinate transformations, thus, enabling on-demand manipulations of electromagnetic waves. However, the application of TO theory in control of hyperbolic waves remains elusive due to the spatial metric signature transition from (+,+) to (-,+) of a two-dimensional hyperbolic geometry. Here, we proposed a distinct Pythagorean theorem, which leads to establishing an anisotropic Fermat’s principle. It helps to construct anisotropic geometries and is a powerful tool for manipulating hyperbolic waves at the nanoscale and polaritons. Making use of absolute instruments, the excellent collimating and focusing behaviors of naturally in-plane hyperbolic polaritons in van der Waals α–MoO3 layers are demonstrated, which opens up a new way for polaritons manipulation.
Photonics Research
- Publication Date: Sep. 30, 2022
- Vol. 10, Issue 10, B14 (2022)
Metasurface empowered lithium niobate optical phased array with an enlarged field of view|Editors' Pick
Zhizhang Wang, Wange Song, Yuxin Chen, Bin Fang, Jitao Ji, Haoran Xin, Shining Zhu, and Tao Li
Integrated optical phased arrays (OPAs) have attracted significant interest to steer laser beams for applications including free-space communications, holography, and light detection and ranging. Although many methods have been proposed to suppress grating lobes, OPAs have also been limited by the trade-off between field of view (FOV) and beamforming efficiency. Here, we propose a metasurface empowered port-selected OPA (POPA), an OPA steered by port selection, which is implemented by an aperiodic waveguide array with an average pitch less than the wavelength and phase controlled by coupling among waveguides. A metasurface layer above the POPA was designed to increase wide FOV steering, aliasing-free by polarization division. As a result, we experimentally demonstrate beam scanning over a ±41.04°×7.06° FOV. The aliasing-free POPA with expanded FOV shows successful incorporation of the waveguide-based OPA technique with an emerging metasurface design, indicating much exploration in concepts for integrated photonic devices. Integrated optical phased arrays (OPAs) have attracted significant interest to steer laser beams for applications including free-space communications, holography, and light detection and ranging. Although many methods have been proposed to suppress grating lobes, OPAs have also been limited by the trade-off between field of view (FOV) and beamforming efficiency. Here, we propose a metasurface empowered port-selected OPA (POPA), an OPA steered by port selection, which is implemented by an aperiodic waveguide array with an average pitch less than the wavelength and phase controlled by coupling among waveguides. A metasurface layer above the POPA was designed to increase wide FOV steering, aliasing-free by polarization division. As a result, we experimentally demonstrate beam scanning over a ±41.04°×7.06° FOV. The aliasing-free POPA with expanded FOV shows successful incorporation of the waveguide-based OPA technique with an emerging metasurface design, indicating much exploration in concepts for integrated photonic devices.
Photonics Research
- Publication Date: Oct. 19, 2022
- Vol. 10, Issue 11, B23 (2022)
High numerical aperture RGB achromatic metalens in the visible
Sangwon Baek, Joohoon Kim, Yeseul Kim, Won Seok Cho, Trevon Badloe, Seong-Won Moon, Junsuk Rho, and Jong-Lam Lee
We theoretically and experimentally demonstrate an RGB achromatic metalens that operates concurrently at three visible wavelengths (λ=450, 532, and 700 nm) with a high numerical aperture of 0.87. The RGB metalens is designed by simple integration of metalens components with the spatial interleaving method. The simulated spatial interleaving metalens shows RGB achromatic operation with focusing efficiencies of 25.2%, 58.7%, and 66.4% at the wavelengths of 450, 532, and 700 nm, respectively. A 450 μm diameter metalens operating at three designated wavelengths is fabricated with low-loss hydrogenated amorphous silicon. The fabricated metalens has the measured focusing efficiencies of 5.9%, 11.3%, and 13.6% at λ=450, 532, and 700 nm, respectively. The Strehl ratios of 0.89, 0.88, and 0.82 are obtained at given wavelengths, which show a capability of diffraction-limited operation. We theoretically and experimentally demonstrate an RGB achromatic metalens that operates concurrently at three visible wavelengths (λ=450, 532, and 700 nm) with a high numerical aperture of 0.87. The RGB metalens is designed by simple integration of metalens components with the spatial interleaving method. The simulated spatial interleaving metalens shows RGB achromatic operation with focusing efficiencies of 25.2%, 58.7%, and 66.4% at the wavelengths of 450, 532, and 700 nm, respectively. A 450 μm diameter metalens operating at three designated wavelengths is fabricated with low-loss hydrogenated amorphous silicon. The fabricated metalens has the measured focusing efficiencies of 5.9%, 11.3%, and 13.6% at λ=450, 532, and 700 nm, respectively. The Strehl ratios of 0.89, 0.88, and 0.82 are obtained at given wavelengths, which show a capability of diffraction-limited operation.
Photonics Research
- Publication Date: Nov. 30, 2022
- Vol. 10, Issue 12, B30 (2022)
Fundamental limits for transmission modulation in VO2 metasurfaces|Editors' Pick
Bohan Li, Rocio Camacho-Morales, Neuton Li, Andrea Tognazzi, Marco Gandolfi, Domenico de Ceglia, Costantino De Angelis, Andrey A. Sukhorukov, and Dragomir N. Neshev
The interest in dynamic modulation of light by ultra-thin materials exhibiting insulator–metal phase transition, such as VO2, has rapidly grown due to the myriad industrial applications, including smart windows and optical limiters. However, for applications in the telecommunication spectral band, the light modulation through a thin VO2 film is low due to the presence of strong material loss. Here, we demonstrate tailored nanostructuring of VO2 to dramatically enhance its transmission modulation, reaching a value as high as 0.73, which is 2 times larger than the previous modulation achieved. The resulting designs, including free-topology optimization, demonstrate the fundamental limit in acquiring the desired optical performance, including achieving positive or negative transmission contrast. Our results on nanophotonic management of lossy nanostructured films open new opportunities for applications of VO2 metasurfaces. The interest in dynamic modulation of light by ultra-thin materials exhibiting insulator–metal phase transition, such as VO2, has rapidly grown due to the myriad industrial applications, including smart windows and optical limiters. However, for applications in the telecommunication spectral band, the light modulation through a thin VO2 film is low due to the presence of strong material loss. Here, we demonstrate tailored nanostructuring of VO2 to dramatically enhance its transmission modulation, reaching a value as high as 0.73, which is 2 times larger than the previous modulation achieved. The resulting designs, including free-topology optimization, demonstrate the fundamental limit in acquiring the desired optical performance, including achieving positive or negative transmission contrast. Our results on nanophotonic management of lossy nanostructured films open new opportunities for applications of VO2 metasurfaces.
Photonics Research
- Publication Date: Dec. 23, 2022
- Vol. 11, Issue 1, B40 (2023)
Nonlinear photonics with metasurfaces
Polina Vabishchevich, and Yuri Kivshar
Nonlinear optics is a well-established field of research that traditionally relies on the interaction of light with macroscopic nonlinear media over distances significantly greater than the wavelength of light. However, the recently emerged field of optical metasurfaces provides a novel platform for studying nonlinear phenomena in planar geometries. Nonlinear optical metasurfaces introduce new functionalities to the field of nonlinear optics extending them beyond perturbative regimes of harmonic generation and parametric frequency conversion, being driven by mode-matching, resonances, and relaxed phase-matching conditions. Here we review the very recent advances in the rapidly developing field of nonlinear metasurface photonics, emphasizing multi-frequency and cascading effects, asymmetric and chiral frequency conversion, nonperturbative nonlinear regimes, and nonlinear quantum photonics, empowered by the physics of Mie resonances and optical bound states in the continuum. Nonlinear optics is a well-established field of research that traditionally relies on the interaction of light with macroscopic nonlinear media over distances significantly greater than the wavelength of light. However, the recently emerged field of optical metasurfaces provides a novel platform for studying nonlinear phenomena in planar geometries. Nonlinear optical metasurfaces introduce new functionalities to the field of nonlinear optics extending them beyond perturbative regimes of harmonic generation and parametric frequency conversion, being driven by mode-matching, resonances, and relaxed phase-matching conditions. Here we review the very recent advances in the rapidly developing field of nonlinear metasurface photonics, emphasizing multi-frequency and cascading effects, asymmetric and chiral frequency conversion, nonperturbative nonlinear regimes, and nonlinear quantum photonics, empowered by the physics of Mie resonances and optical bound states in the continuum.
Photonics Research
- Publication Date: Jan. 30, 2023
- Vol. 11, Issue 2, B50 (2023)
Topological metasurface: from passive toward active and beyond
Jian Wei You, Zhihao Lan, Qian Ma, Zhen Gao, Yihao Yang, Fei Gao, Meng Xiao, and Tie Jun Cui
Metasurfaces are subwavelength structured thin films consisting of arrays of units that allow the control of polarization, phase, and amplitude of light over a subwavelength thickness. Recent developments in topological photonics have greatly broadened the horizon in designing metasurfaces for novel functional applications. In this review, we summarize recent progress in the research field of topological metasurfaces, first from the perspectives of passive and active in the classical regime, and then in the quantum regime. More specifically, we begin by examining the passive topological phenomena in two-dimensional photonic systems, including both time-reversal broken systems and time-reversal preserved systems. Subsequently, we discuss the cutting-edge studies of active topological metasurfaces, including nonlinear topological metasurfaces and reconfigurable topological metasurfaces. After overviewing topological metasurfaces in the classical regime, we show how they could provide a new platform for quantum information and quantum many-body physics. Finally, we conclude and describe some challenges and future directions of this fast-evolving field. Metasurfaces are subwavelength structured thin films consisting of arrays of units that allow the control of polarization, phase, and amplitude of light over a subwavelength thickness. Recent developments in topological photonics have greatly broadened the horizon in designing metasurfaces for novel functional applications. In this review, we summarize recent progress in the research field of topological metasurfaces, first from the perspectives of passive and active in the classical regime, and then in the quantum regime. More specifically, we begin by examining the passive topological phenomena in two-dimensional photonic systems, including both time-reversal broken systems and time-reversal preserved systems. Subsequently, we discuss the cutting-edge studies of active topological metasurfaces, including nonlinear topological metasurfaces and reconfigurable topological metasurfaces. After overviewing topological metasurfaces in the classical regime, we show how they could provide a new platform for quantum information and quantum many-body physics. Finally, we conclude and describe some challenges and future directions of this fast-evolving field.
Photonics Research
- Publication Date: Feb. 13, 2023
- Vol. 11, Issue 3, B65 (2023)
High-throughput fabrication of large-scale metasurfaces using electron-beam lithography with SU-8 gratings for multilevel security printing|Spotlight on Optics
You Sin Tan, Hao Wang, Hongtao Wang, Chengfeng Pan, and Joel K. W. Yang
The field of metasurface research has rapidly developed in the past decade. Electron-beam lithography (EBL) is an excellent tool used for rapid prototyping of metasurfaces. However, Gaussian-beam EBL generally struggles with low throughput. In conjunction with the recent rise of interest in metasurfaces made of low-index dielectric materials, we propose in this study the use of a relatively unexplored chemically amplified resist, SU-8 with EBL, as a method for rapid prototyping of low-index metasurfaces. We demonstrate the use of SU-8 grating on silicon for cost-efficient fabrication of an all-dielectric multilevel security print for anti-counterfeiting purposes, which encrypt different optical information with different light illumination conditions, namely, bright-field reflection, dark-field reflection, and cross-polarized reflection. The large-scale print (1 mm2) could be exposed in a relatively short time (∼11 min) due to the ultrahigh sensitivity of the resist, while the feature size of ∼200 nm was maintained, demonstrating that SU-8 EBL resist serves as a good candidate for rapid prototyping of metasurface designs. Our results could find applications in the general area of increasing EBL patterning speed for a variety of other devices and structures. The field of metasurface research has rapidly developed in the past decade. Electron-beam lithography (EBL) is an excellent tool used for rapid prototyping of metasurfaces. However, Gaussian-beam EBL generally struggles with low throughput. In conjunction with the recent rise of interest in metasurfaces made of low-index dielectric materials, we propose in this study the use of a relatively unexplored chemically amplified resist, SU-8 with EBL, as a method for rapid prototyping of low-index metasurfaces. We demonstrate the use of SU-8 grating on silicon for cost-efficient fabrication of an all-dielectric multilevel security print for anti-counterfeiting purposes, which encrypt different optical information with different light illumination conditions, namely, bright-field reflection, dark-field reflection, and cross-polarized reflection. The large-scale print (1 mm2) could be exposed in a relatively short time (∼11 min) due to the ultrahigh sensitivity of the resist, while the feature size of ∼200 nm was maintained, demonstrating that SU-8 EBL resist serves as a good candidate for rapid prototyping of metasurface designs. Our results could find applications in the general area of increasing EBL patterning speed for a variety of other devices and structures.
Photonics Research
- Publication Date: Feb. 27, 2023
- Vol. 11, Issue 3, B103 (2023)
Guest Editors:
Guixin Li
Southern University of Science and Technology, China (Lead Editor)
Thomas Pertsch
Friedrich-Schiller-Universität Jena, Germany
Arka Majumdar
University of Washington, USA
Shumin Xiao
Harbin Institute of Technology (Shenzhen), China
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