Journals > > Topics > Nanophotonics and Photonic Crystals
Nanophotonics and Photonic Crystals|63 Article(s)
Optically induced rotation of Rayleigh particles by arbitrary photonic spin
Guanghao Rui, Ying Li, Sichao Zhou, Yusong Wang, Bing Gu, Yiping Cui, and Qiwen Zhan
Optical trapping techniques hold great interest for their advantages that enable direct handling of nanoparticles. In this work, we study the optical trapping effects of a diffraction-limited focal field possessing an arbitrary photonic spin and propose a convenient method to manipulate the movement behavior of the trapped nanoparticles. In order to achieve controllable spin axis orientation and ellipticity of the tightly focused beam in three dimensions, an efficient method to analytically calculate and experimentally generate complex optical fields at the pupil plane of a high numerical aperture lens is developed. By numerically calculating the optical forces and torques of Rayleigh particles with spherical/ellipsoidal shape, we demonstrate that the interactions between the tunable photonic spin and nanoparticles lead to not only 3D trapping but also precise control of the nanoparticles’ movements in terms of stable orientation, rotational orientation, and rotation frequency. This versatile trapping method may open up new avenues for optical trapping and their applications in various scientific fields. Optical trapping techniques hold great interest for their advantages that enable direct handling of nanoparticles. In this work, we study the optical trapping effects of a diffraction-limited focal field possessing an arbitrary photonic spin and propose a convenient method to manipulate the movement behavior of the trapped nanoparticles. In order to achieve controllable spin axis orientation and ellipticity of the tightly focused beam in three dimensions, an efficient method to analytically calculate and experimentally generate complex optical fields at the pupil plane of a high numerical aperture lens is developed. By numerically calculating the optical forces and torques of Rayleigh particles with spherical/ellipsoidal shape, we demonstrate that the interactions between the tunable photonic spin and nanoparticles lead to not only 3D trapping but also precise control of the nanoparticles’ movements in terms of stable orientation, rotational orientation, and rotation frequency. This versatile trapping method may open up new avenues for optical trapping and their applications in various scientific fields.
Photonics Research
- Publication Date: Jan. 01, 2019
- Vol. 7, Issue 1, 01000069 (2019)
Coherent couplings between magnetic dipole transitions of quantum emitters and dielectric nanostructures
Qian Zhao, Zhong-Jian Yang, and Jun He
Here we study theoretically the optical responses of hybrid structures composed of dielectric nanostructures and quantum emitters with magnetic dipole transitions. Coherent couplings between magnetic dipole transitions and magnetic modes can occur, leading to giant modifications of the extinction spectra of the constituents in the hybrid structures. For a given hybrid structure, the extinction-cross-section spectra show linear or nonlinear behaviors depending on the strength of the excitation field. For a weak excitation, the extinction of the quantum emitters is greatly enhanced. The hybrid structure shows a dip on its extinction spectrum. For a strong excitation, the resonant extinction of the quantum emitters is weakly enhanced while the extinction spectrum is broadened obviously. The hybrid structure shows a Fano-like line shape on its extinction spectrum, which is different from that with a weak excitation. This difference is highly related to the behaviors of the magnetic polarizabilities of the quantum emitters in the hybrid structure. The optical responses of hybrid structures can be largely tuned by varying the geometric and material parameters. Here we study theoretically the optical responses of hybrid structures composed of dielectric nanostructures and quantum emitters with magnetic dipole transitions. Coherent couplings between magnetic dipole transitions and magnetic modes can occur, leading to giant modifications of the extinction spectra of the constituents in the hybrid structures. For a given hybrid structure, the extinction-cross-section spectra show linear or nonlinear behaviors depending on the strength of the excitation field. For a weak excitation, the extinction of the quantum emitters is greatly enhanced. The hybrid structure shows a dip on its extinction spectrum. For a strong excitation, the resonant extinction of the quantum emitters is weakly enhanced while the extinction spectrum is broadened obviously. The hybrid structure shows a Fano-like line shape on its extinction spectrum, which is different from that with a weak excitation. This difference is highly related to the behaviors of the magnetic polarizabilities of the quantum emitters in the hybrid structure. The optical responses of hybrid structures can be largely tuned by varying the geometric and material parameters.
Photonics Research
- Publication Date: Sep. 18, 2019
- Vol. 7, Issue 10, 10001142 (2019)
Nanophotonic media for artificial neural inference|On the Cover
Erfan Khoram, Ang Chen, Dianjing Liu, Lei Ying, Qiqi Wang, Ming Yuan, and Zongfu Yu
We show optical waves passing through a nanophotonic medium can perform artificial neural computing. Complex information is encoded in the wavefront of an input light. The medium transforms the wavefront to realize sophisticated computing tasks such as image recognition. At the output, the optical energy is concentrated in well-defined locations, which, for example, can be interpreted as the identity of the object in the image. These computing media can be as small as tens of wavelengths and offer ultra-high computing density. They exploit subwavelength scatterers to realize complex input/output mapping beyond the capabilities of traditional nanophotonic devices. We show optical waves passing through a nanophotonic medium can perform artificial neural computing. Complex information is encoded in the wavefront of an input light. The medium transforms the wavefront to realize sophisticated computing tasks such as image recognition. At the output, the optical energy is concentrated in well-defined locations, which, for example, can be interpreted as the identity of the object in the image. These computing media can be as small as tens of wavelengths and offer ultra-high computing density. They exploit subwavelength scatterers to realize complex input/output mapping beyond the capabilities of traditional nanophotonic devices.
Photonics Research
- Publication Date: Jul. 08, 2019
- Vol. 7, Issue 8, 08000823 (2019)
Weak measurement of the magneto-optical spin Hall effect of light
Jie Li, Tingting Tang, Li Luo, Jian Shen, Chaoyang Li, Jun Qin, and Lei Bi
The spin Hall effect of light (SHEL) is a photonic version of the spin Hall effect in electronic systems and has been studied for more than 10 years. However, the lack of effective methods for dynamic modulation of spin-dependent splitting may hinder its applications. By introducing additional spin-orbit coupling of photons or nonreciprocal phase shift (NRPS), the magneto-optical Kerr effect may be one of the methods to alleviate the situation. Here, we experimentally reveal an enhanced and tunable SHEL in magneto-optical oxide thin films under the transverse magneto-optical Kerr effect configuration for the first time, to the best of our knowledge, which can be regarded as the magneto-optical SHEL (MOSHEL). We study the magneto-optical response of the multilayer structure and select the optimal structural parameters by the magneto-optical transfer matrix method. With a transverse magnetic field along opposite directions, an obvious SHEL shift difference of H-polarized light caused by NRPS is observed via a weak measurement method. With optimal parameters, the maximum measured shift difference of the SHEL achieves about 70 μm. The demonstrated MOSHEL phenomenon may accelerate the application of the SHEL in the field of spin photonics devices and precision metrology. The spin Hall effect of light (SHEL) is a photonic version of the spin Hall effect in electronic systems and has been studied for more than 10 years. However, the lack of effective methods for dynamic modulation of spin-dependent splitting may hinder its applications. By introducing additional spin-orbit coupling of photons or nonreciprocal phase shift (NRPS), the magneto-optical Kerr effect may be one of the methods to alleviate the situation. Here, we experimentally reveal an enhanced and tunable SHEL in magneto-optical oxide thin films under the transverse magneto-optical Kerr effect configuration for the first time, to the best of our knowledge, which can be regarded as the magneto-optical SHEL (MOSHEL). We study the magneto-optical response of the multilayer structure and select the optimal structural parameters by the magneto-optical transfer matrix method. With a transverse magnetic field along opposite directions, an obvious SHEL shift difference of H-polarized light caused by NRPS is observed via a weak measurement method. With optimal parameters, the maximum measured shift difference of the SHEL achieves about 70 μm. The demonstrated MOSHEL phenomenon may accelerate the application of the SHEL in the field of spin photonics devices and precision metrology.
Photonics Research
- Publication Date: Aug. 12, 2019
- Vol. 7, Issue 9, 09001014 (2019)
Dual-band and ultra-broadband photonic spin-orbit interaction for electromagnetic shaping based on single-layer silicon metasurfaces|On the Cover
Xin Xie, Mingbo Pu, Xiong Li, Kaipeng Liu, Jinjin Jin, Xiaoliang Ma, and Xiangang Luo
Achieving electromagnetic wave scattering manipulation in the multispectral and broad operation band has been a long pursuit in stealth applications. Here, we present an approach by using single-layer metasurfaces composed of space-variant amorphous silicon ridges tiled on a metallic mirror, to generate high-efficiency dual-band and ultra-wideband photonic spin-orbit interaction and geometric phase. Two scattering engineered metasurfaces have been designed to reduce specular reflection; the first one can suppress both specular reflectances at 1.05–1.08 μm and 5–12 μm below 10%. The second one is designed for an ultra-broadband of 4.6–14 μm, which is actually implemented by cleverly connecting two bands of 4.6–6.1 μm and 6.1–14 μm. Furthermore, the presented structures exhibit low thermal emission at the same time due to the low absorption loss of silicon in the infrared spectrum, which can be regarded as an achievement of laser–infrared compatible camouflage. We believe the proposed strategy may open a new route to implement multispectral electromagnetic modulation and multiphysical engineering applications. Achieving electromagnetic wave scattering manipulation in the multispectral and broad operation band has been a long pursuit in stealth applications. Here, we present an approach by using single-layer metasurfaces composed of space-variant amorphous silicon ridges tiled on a metallic mirror, to generate high-efficiency dual-band and ultra-wideband photonic spin-orbit interaction and geometric phase. Two scattering engineered metasurfaces have been designed to reduce specular reflection; the first one can suppress both specular reflectances at 1.05–1.08 μm and 5–12 μm below 10%. The second one is designed for an ultra-broadband of 4.6–14 μm, which is actually implemented by cleverly connecting two bands of 4.6–6.1 μm and 6.1–14 μm. Furthermore, the presented structures exhibit low thermal emission at the same time due to the low absorption loss of silicon in the infrared spectrum, which can be regarded as an achievement of laser–infrared compatible camouflage. We believe the proposed strategy may open a new route to implement multispectral electromagnetic modulation and multiphysical engineering applications.
Photonics Research
- Publication Date: Apr. 30, 2019
- Vol. 7, Issue 5, 05000586 (2019)
Compact CMOS spectral sensor for the visible spectrum|Editors' Pick
Yibo Zhu, Xin Lei, Ken Xingze Wang, and Zongfu Yu
A compact single-shot complementary metal-oxide semiconductor (CMOS) spectral sensor for the visible range (wavelength 400–700 nm) is presented. The sensor consists of two-dimensional silicon nitride-based photonic crystal (PC) slabs atop CMOS photodetectors. The PC slabs are fabricated using one-step lithography and amenable to monolithic integration into CMOS image sensors. Featuring a small footprint of 300 μm×350 μm, the sensor can successfully measure the spectra over the 400–700 wavelength range with a best resolution of 1 nm. The footprint of the sensor may be further reduced to enable hyperspectral imaging with high spatial resolution. A compact single-shot complementary metal-oxide semiconductor (CMOS) spectral sensor for the visible range (wavelength 400–700 nm) is presented. The sensor consists of two-dimensional silicon nitride-based photonic crystal (PC) slabs atop CMOS photodetectors. The PC slabs are fabricated using one-step lithography and amenable to monolithic integration into CMOS image sensors. Featuring a small footprint of 300 μm×350 μm, the sensor can successfully measure the spectra over the 400–700 wavelength range with a best resolution of 1 nm. The footprint of the sensor may be further reduced to enable hyperspectral imaging with high spatial resolution.
Photonics Research
- Publication Date: Aug. 05, 2019
- Vol. 7, Issue 9, 09000961 (2019)
Freestanding metal nanohole array for high-performance applications
Bobo Du, Yinlan Ruan, Dexing Yang, Peipei Jia, Shoufei Gao, Yingying Wang, Pu Wang, and Heike Ebendorff-Heidepriem
Plasmonic devices using periodic metallic nanostructures have recently gained tremendous interest for color filters, sensing, surface enhanced spectroscopy, and enhanced photoluminescence, etc. However, the performance of such plasmonic devices is severely hampered by the solid substrates supporting the metallic nanostructures. Here, a strategy for freestanding metallic nanomembranes is introduced by taking advantages of hollow substrate structures. Large-area and highly uniform gold nanomembranes with nanohole array are fabricated via a flexible and simple replication-releasing method. The hollow structures include a hollow core fiber with 30 μm core diameter and two ferrules with their hole diameter as 125 and 500 μm, respectively. As a proof-of-concept demonstration, 2 times higher sensitivity of the bulk refractive index is obtained with this platform compared to that of a counterpart on a solid silica substrate. Such a portable and compact configuration provides unique opportunities to explore the intrinsic properties of the metal nanomembranes and paves a new way to fabricate high-performance plasmonic devices for biomolecule sensing and color filter. Plasmonic devices using periodic metallic nanostructures have recently gained tremendous interest for color filters, sensing, surface enhanced spectroscopy, and enhanced photoluminescence, etc. However, the performance of such plasmonic devices is severely hampered by the solid substrates supporting the metallic nanostructures. Here, a strategy for freestanding metallic nanomembranes is introduced by taking advantages of hollow substrate structures. Large-area and highly uniform gold nanomembranes with nanohole array are fabricated via a flexible and simple replication-releasing method. The hollow structures include a hollow core fiber with 30 μm core diameter and two ferrules with their hole diameter as 125 and 500 μm, respectively. As a proof-of-concept demonstration, 2 times higher sensitivity of the bulk refractive index is obtained with this platform compared to that of a counterpart on a solid silica substrate. Such a portable and compact configuration provides unique opportunities to explore the intrinsic properties of the metal nanomembranes and paves a new way to fabricate high-performance plasmonic devices for biomolecule sensing and color filter.
Photonics Research
- Publication Date: Oct. 22, 2020
- Vol. 8, Issue 11, 11001749 (2020)
Design of a multichannel photonic crystal dielectric laser accelerator
Zhexin Zhao, Dylan S. Black, R. Joel England, Tyler W. Hughes, Yu Miao, Olav Solgaard, Robert L. Byer, and Shanhui Fan
To be useful for most scientific and medical applications, compact particle accelerators will require much higher average current than enabled by current architectures. For this purpose, we propose a photonic crystal architecture for a dielectric laser accelerator, referred to as a multi-input multi-output silicon accelerator (MIMOSA), that enables simultaneous acceleration of multiple electron beams, increasing the total electron throughput by at least 1 order of magnitude. To achieve this, we show that the photonic crystal must support a mode at the Γ point in reciprocal space, with a normalized frequency equal to the normalized speed of the phase-matched electron. We show that the figure of merit of the MIMOSA can be inferred from the eigenmodes of the corresponding infinitely periodic structure, which provides a powerful approach to design such devices. Additionally, we extend the MIMOSA architecture to electron deflectors and other electron manipulation functionalities. These additional functionalities, combined with the increased electron throughput of these devices, permit all-optical on-chip manipulation of electron beams in a fully integrated architecture compatible with current fabrication technologies, which opens the way to unconventional electron beam shaping, imaging, and radiation generation. To be useful for most scientific and medical applications, compact particle accelerators will require much higher average current than enabled by current architectures. For this purpose, we propose a photonic crystal architecture for a dielectric laser accelerator, referred to as a multi-input multi-output silicon accelerator (MIMOSA), that enables simultaneous acceleration of multiple electron beams, increasing the total electron throughput by at least 1 order of magnitude. To achieve this, we show that the photonic crystal must support a mode at the Γ point in reciprocal space, with a normalized frequency equal to the normalized speed of the phase-matched electron. We show that the figure of merit of the MIMOSA can be inferred from the eigenmodes of the corresponding infinitely periodic structure, which provides a powerful approach to design such devices. Additionally, we extend the MIMOSA architecture to electron deflectors and other electron manipulation functionalities. These additional functionalities, combined with the increased electron throughput of these devices, permit all-optical on-chip manipulation of electron beams in a fully integrated architecture compatible with current fabrication technologies, which opens the way to unconventional electron beam shaping, imaging, and radiation generation.
Photonics Research
- Publication Date: Sep. 21, 2020
- Vol. 8, Issue 10, 10001586 (2020)
Neuromorphic metasurface|Spotlight on Optics
Zhicheng Wu, Ming Zhou, Erfan Khoram, Boyuan Liu, and Zongfu Yu
Metasurfaces have been used to realize optical functions such as focusing and beam steering. They use subwavelength nanostructures to control the local amplitude and phase of light. Here we show that such control could also enable a new function of artificial neural inference. We demonstrate that metasurfaces can directly recognize objects by focusing light from an object to different spatial locations that correspond to the class of the object. Metasurfaces have been used to realize optical functions such as focusing and beam steering. They use subwavelength nanostructures to control the local amplitude and phase of light. Here we show that such control could also enable a new function of artificial neural inference. We demonstrate that metasurfaces can directly recognize objects by focusing light from an object to different spatial locations that correspond to the class of the object.
Photonics Research
- Publication Date: Jan. 01, 2020
- Vol. 8, Issue 1, 01000046 (2020)
Effects of third-order dispersion on temporal soliton compression in dispersion-engineered silicon photonic crystal waveguides
Jiali Liao, Yang Gao, Yanling Sun, Lin Ma, Zhenzhong Lu, and Xiujian Li
High-order temporal soliton compression in dispersion-engineered silicon photonic crystal waveguides will play an important role in future integrated photonic circuits compatible with complementary metal–oxide–semiconductors. Here, we report the physical mechanisms of high-order temporal soliton compression affected by third-order dispersion (TOD) combined with free carrier dispersion (FCD) in a dispersion engineered silicon photonic crystal waveguide with wideband low anomalous dispersion. Through numerical temporal soliton evolution analysis, we report what we believe is the first demonstration of the dual opposite effects of TOD on temporal soliton compression, which are strengthening or weakening through two different physical mechanisms, not only depending on the sign of TOD but also the relative magnitude of TOD-induced equivalent group velocity dispersion (GVD) β2,equ to the original GVD β2. We further find that FCD counteracts the effects of negative TOD on the soliton compression, while it reinforces the effects of positive TOD on the soliton compression. These results will help to design suitable dispersion-engineered silicon waveguides for superior on-chip temporal pulse compression in optical communications and processing application fields. High-order temporal soliton compression in dispersion-engineered silicon photonic crystal waveguides will play an important role in future integrated photonic circuits compatible with complementary metal–oxide–semiconductors. Here, we report the physical mechanisms of high-order temporal soliton compression affected by third-order dispersion (TOD) combined with free carrier dispersion (FCD) in a dispersion engineered silicon photonic crystal waveguide with wideband low anomalous dispersion. Through numerical temporal soliton evolution analysis, we report what we believe is the first demonstration of the dual opposite effects of TOD on temporal soliton compression, which are strengthening or weakening through two different physical mechanisms, not only depending on the sign of TOD but also the relative magnitude of TOD-induced equivalent group velocity dispersion (GVD) β2,equ to the original GVD β2. We further find that FCD counteracts the effects of negative TOD on the soliton compression, while it reinforces the effects of positive TOD on the soliton compression. These results will help to design suitable dispersion-engineered silicon waveguides for superior on-chip temporal pulse compression in optical communications and processing application fields.
Photonics Research
- Publication Date: Apr. 24, 2020
- Vol. 8, Issue 5, 05000729 (2020)
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