Journals > > Topics > Nanophotonics and Photonic Crystals
Nanophotonics and Photonic Crystals|84 Article(s)
Arbitrary hue-brightness structural colors with high saturation generated by anisotropic metasurfaces
Chong Wang, He Li, Longjie Li, Xiao Shang, Shengqiong Chen, Huiwen Xue, Peiwen Zhang, Jiebin Niu, Yongliang Zhang, and Lina Shi
Structural colors have always attracted much attention due to important applications in display devices, imaging security certification, optical data storage, and so on. The brightness of structure colors, as the carrier of chiaroscuro information, is the key to making images appear stronger in the spatial and three-dimensional sense. However, relatively little work has been done on the control of the color brightness, and the reported structures are complex and difficult to fabricate. Here, we demonstrate a low-aspect-ratio anisotropic metasurface consisting of a PMMA film patterned by arrays of elliptical-shaped holes clamped by two thin aluminum films. By utilizing localized surface plasmon resonances, we realize a three-dimensional (3D) HSB (hue, saturation, and brightness) structure color with independent brightness control and enhance the cross-polarization reflection, covering approximately 120% of the sRGB color gamut. It is shown that the ratio of the major and minor axes leads to the independent control of brightness of the structural colors. The nanoprinting of HSB images with smooth brightness transitions is demonstrated through elaborate design of the metasurface geometry parameters and CMOS-compatible micro–nano fabrication process. Our findings will facilitate the broad range of 3D nanoprinting and modern advanced display applications. Structural colors have always attracted much attention due to important applications in display devices, imaging security certification, optical data storage, and so on. The brightness of structure colors, as the carrier of chiaroscuro information, is the key to making images appear stronger in the spatial and three-dimensional sense. However, relatively little work has been done on the control of the color brightness, and the reported structures are complex and difficult to fabricate. Here, we demonstrate a low-aspect-ratio anisotropic metasurface consisting of a PMMA film patterned by arrays of elliptical-shaped holes clamped by two thin aluminum films. By utilizing localized surface plasmon resonances, we realize a three-dimensional (3D) HSB (hue, saturation, and brightness) structure color with independent brightness control and enhance the cross-polarization reflection, covering approximately 120% of the sRGB color gamut. It is shown that the ratio of the major and minor axes leads to the independent control of brightness of the structural colors. The nanoprinting of HSB images with smooth brightness transitions is demonstrated through elaborate design of the metasurface geometry parameters and CMOS-compatible micro–nano fabrication process. Our findings will facilitate the broad range of 3D nanoprinting and modern advanced display applications.
Photonics Research
- Publication Date: Feb. 28, 2025
- Vol. 13, Issue 3, 772 (2025)
Si/Si3N4/Ag hybrid nanocavity: a platform for enhancing light-matter interaction|Editors' Pick
Tianqi Peng, Zhuo Wang, Shulei Li, Lidan Zhou, Shimei Liu, Yuheng Mao, Mingcheng Panmai, Weichen He, and Sheng Lan
High-index dielectric nanoparticles supporting strong Mie resonances, such as silicon (Si) nanoparticles, provide a platform for manipulating optical fields at the subwavelength scale. However, in general, the quality factors of Mie resonances supported by an isolated nanoparticle are not sufficient for realizing strong light-matter interaction. Here, we propose the use of dielectric-metal hybrid nanocavities composed of Si nanoparticles and silicon nitride/silver (Si3N4/Ag) heterostructures to improve light-matter interaction. First, we demonstrate that the nonlinear optical absorption of the Si nanoparticle in a Si/Si3N4/Ag hybrid nanocavity can be greatly enhanced at the magnetic dipole resonance. The Si/Si3N4/Ag nanocavity exhibits luminescence burst at substantially lower excitation energy (∼20.5 pJ) compared to a Si nanoparticle placed on a silica substrate (∼51.3 pJ). The luminescence intensity is also enhanced by an order of magnitude. Second, we show that strong exciton-photon coupling can be realized when a tungsten disulfide (WS2) monolayer is inserted into a Si/Si3N4/Ag nanocavity. When such a system is excited by using s-polarized light, the optical resonance supported by the nanocavity can be continuously tuned to sweep across the two exciton resonances of the WS2 monolayer by simply varying the incident angle. As a result, Rabi splitting energies as large as ∼146.4 meV and ∼110 meV are observed at the A- and B-exciton resonances of the WS2 monolayer, satisfying the criterion for strong exciton-photon coupling. The proposed nanocavities provide, to our knowledge, a new platform for enhancing light-matter interaction in multiple scenarios and imply potential applications in constructing nanoscale photonic devices. High-index dielectric nanoparticles supporting strong Mie resonances, such as silicon (Si) nanoparticles, provide a platform for manipulating optical fields at the subwavelength scale. However, in general, the quality factors of Mie resonances supported by an isolated nanoparticle are not sufficient for realizing strong light-matter interaction. Here, we propose the use of dielectric-metal hybrid nanocavities composed of Si nanoparticles and silicon nitride/silver (Si3N4/Ag) heterostructures to improve light-matter interaction. First, we demonstrate that the nonlinear optical absorption of the Si nanoparticle in a Si/Si3N4/Ag hybrid nanocavity can be greatly enhanced at the magnetic dipole resonance. The Si/Si3N4/Ag nanocavity exhibits luminescence burst at substantially lower excitation energy (∼20.5 pJ) compared to a Si nanoparticle placed on a silica substrate (∼51.3 pJ). The luminescence intensity is also enhanced by an order of magnitude. Second, we show that strong exciton-photon coupling can be realized when a tungsten disulfide (WS2) monolayer is inserted into a Si/Si3N4/Ag nanocavity. When such a system is excited by using s-polarized light, the optical resonance supported by the nanocavity can be continuously tuned to sweep across the two exciton resonances of the WS2 monolayer by simply varying the incident angle. As a result, Rabi splitting energies as large as ∼146.4 meV and ∼110 meV are observed at the A- and B-exciton resonances of the WS2 monolayer, satisfying the criterion for strong exciton-photon coupling. The proposed nanocavities provide, to our knowledge, a new platform for enhancing light-matter interaction in multiple scenarios and imply potential applications in constructing nanoscale photonic devices.
Photonics Research
- Publication Date: Feb. 28, 2025
- Vol. 13, Issue 3, 709 (2025)
Single plasmonic exceptional point nanoantenna coupled to a photonic integrated circuit sensor|Editors' Pick
Kamyar Behrouzi, Zhanni Wu, Liwei Lin, and Boubacar Kante
Point-of-care sensors are pivotal for early disease diagnosis, significantly advancing global health. Surface plasmons, the collective oscillations of free electrons under electromagnetic excitation, have been widely studied for biosensing due to their electromagnetic field enhancements at sub-wavelength scales. We introduce a plasmonic biosensor on a compact photonic integrated circuit (PIC) enhanced by exceptional points (EPs). EPs, singularities in non-Hermitian optical systems, provide extreme sensitivity to external perturbations. They emerge when two or more complex resonating modes merge into a single degenerate mode. We demonstrate an EP in a single coupled nanoantenna particle positioned in a uniquely designed silicon nitride slot-waveguide, which we call a junction-waveguide. By laterally shifting two optically coupled gold nanobars of different lengths, we achieve a single particle EP. The junction-waveguide enables efficient coupling of the plasmonic nanoantenna to the waveguide mode. The system integrates a four-port Mach–Zehnder interferometer (MZI), allowing for simultaneous measurements of the amplitude and phase of EP, facilitating highly accurate real-time eigenvalue extraction. For biosensing, we encapsulated the detection zone with a microchannel, enabling low-volume and simple sample handling. Our single particle integrated EP sensor demonstrates superior sensitivity compared to the corresponding linear diabolic point (DP) system under both local and bulk sensing schemes, even at large perturbations. Our studies revealed that the integrated EP sensor can detect a single molecule captured by the nanobars with the average size ranging from 10 to 100 nm. The proposed EP biosensor, with its extreme sensitivity, compact form, and real-time phase sensing capabilities, provides an approach for detecting and quantifying various biomarkers such as proteins and nucleic acids, offering a unique platform for early disease diagnosis. Point-of-care sensors are pivotal for early disease diagnosis, significantly advancing global health. Surface plasmons, the collective oscillations of free electrons under electromagnetic excitation, have been widely studied for biosensing due to their electromagnetic field enhancements at sub-wavelength scales. We introduce a plasmonic biosensor on a compact photonic integrated circuit (PIC) enhanced by exceptional points (EPs). EPs, singularities in non-Hermitian optical systems, provide extreme sensitivity to external perturbations. They emerge when two or more complex resonating modes merge into a single degenerate mode. We demonstrate an EP in a single coupled nanoantenna particle positioned in a uniquely designed silicon nitride slot-waveguide, which we call a junction-waveguide. By laterally shifting two optically coupled gold nanobars of different lengths, we achieve a single particle EP. The junction-waveguide enables efficient coupling of the plasmonic nanoantenna to the waveguide mode. The system integrates a four-port Mach–Zehnder interferometer (MZI), allowing for simultaneous measurements of the amplitude and phase of EP, facilitating highly accurate real-time eigenvalue extraction. For biosensing, we encapsulated the detection zone with a microchannel, enabling low-volume and simple sample handling. Our single particle integrated EP sensor demonstrates superior sensitivity compared to the corresponding linear diabolic point (DP) system under both local and bulk sensing schemes, even at large perturbations. Our studies revealed that the integrated EP sensor can detect a single molecule captured by the nanobars with the average size ranging from 10 to 100 nm. The proposed EP biosensor, with its extreme sensitivity, compact form, and real-time phase sensing capabilities, provides an approach for detecting and quantifying various biomarkers such as proteins and nucleic acids, offering a unique platform for early disease diagnosis.
Photonics Research
- Publication Date: Feb. 24, 2025
- Vol. 13, Issue 3, 632 (2025)
Multi-frequency terahertz Smith–Purcell radiation via momentum-mismatch-driven quasi-bound states in the continuum
Zi-Wen Zhang, Juan-Feng Zhu, Feng-Yuan Han, Xiao Lin, and Chao-Hai Du
Bound states in the continuum (BICs) have gained considerable attention for their ability to strengthen light–matter interactions, enabling applications in lasing, sensing, and imaging. These properties also show great promise for intensifying free-electron radiation. Recently, researchers realized momentum-mismatch-driven quasi-BICs in compound grating waveguides. This category of quasi-BICs exhibits high Q factors over a broad frequency spectrum. In this paper, we explore the possibility of achieving multi-frequency terahertz Smith–Purcell radiation empowered by momentum-mismatch-driven quasi-BICs in silicon compound grating waveguides. By leveraging the low-loss properties of silicon in the terahertz range, quasi-BICs are achieved through guided-mode resonance, delivering exceptionally high Q factors over a broad frequency spectrum. The broadband nature of these quasi-BICs enables efficient energy extraction from electron beams across varying voltages, while their multimode characteristics support simultaneous interactions with multiple modes, further boosting radiation intensity. The findings demonstrate significant enhancement of free-electron radiation at multiple frequencies, addressing the limitations of narrowband methods and high-loss metallic systems. By integrating broadband performance with the advantages of low-loss dielectric platforms, this work advances the development of compact, tunable terahertz free-electron radiation sources and provides valuable insights into optimizing quasi-BIC systems for practical applications. Bound states in the continuum (BICs) have gained considerable attention for their ability to strengthen light–matter interactions, enabling applications in lasing, sensing, and imaging. These properties also show great promise for intensifying free-electron radiation. Recently, researchers realized momentum-mismatch-driven quasi-BICs in compound grating waveguides. This category of quasi-BICs exhibits high Q factors over a broad frequency spectrum. In this paper, we explore the possibility of achieving multi-frequency terahertz Smith–Purcell radiation empowered by momentum-mismatch-driven quasi-BICs in silicon compound grating waveguides. By leveraging the low-loss properties of silicon in the terahertz range, quasi-BICs are achieved through guided-mode resonance, delivering exceptionally high Q factors over a broad frequency spectrum. The broadband nature of these quasi-BICs enables efficient energy extraction from electron beams across varying voltages, while their multimode characteristics support simultaneous interactions with multiple modes, further boosting radiation intensity. The findings demonstrate significant enhancement of free-electron radiation at multiple frequencies, addressing the limitations of narrowband methods and high-loss metallic systems. By integrating broadband performance with the advantages of low-loss dielectric platforms, this work advances the development of compact, tunable terahertz free-electron radiation sources and provides valuable insights into optimizing quasi-BIC systems for practical applications.
Photonics Research
- Publication Date: Feb. 18, 2025
- Vol. 13, Issue 3, 593 (2025)
Rotation-induced plasmonic chiral quasi-bound states in the continuum
Chunhua Qin, Yadong Deng, Tianshuo Lyu, Chao Meng, Sören Im Sande, Sergey I. Bozhevolnyi, Jinhui Shi, and Fei Ding
Nanoscale light manipulation using plasmonic metasurfaces has emerged as a frontier in photonic research, offering strongly enhanced light–matter interactions with potential applications in sensing, communications, and quantum optics. Here, we unveil the realization and control of chiral quasi-bound states in the continuum (quasi-BICs) by judiciously rotating one of the paired plasmonic bricks and thereby influencing structural asymmetry. By precisely controlling the rotation angle, we enable continuous modulation of the radiation loss in quasi-BICs and transition from a perfect half-wave plate to a good absorber for the left-handed circularly polarized light. This transformation leverages the intrinsic chirality with moderately high circular dichroism of ∼0.35 in both simulation and experimental observations, manifesting unprecedented control over the chiral light within sub-wavelength scales. Theoretical modeling and numerical simulations complement our experimental findings, offering deep insights into underlying mechanisms and the role of symmetry breaking in realizing chiral quasi-BICs. The observed phenomena open new pathways for developing ultra-compact chiral photonic devices with tailored optical properties, including highly sensitive chiral biosensors, circular dichroism spectroscopy, and chiral flat optical components for information processing. Nanoscale light manipulation using plasmonic metasurfaces has emerged as a frontier in photonic research, offering strongly enhanced light–matter interactions with potential applications in sensing, communications, and quantum optics. Here, we unveil the realization and control of chiral quasi-bound states in the continuum (quasi-BICs) by judiciously rotating one of the paired plasmonic bricks and thereby influencing structural asymmetry. By precisely controlling the rotation angle, we enable continuous modulation of the radiation loss in quasi-BICs and transition from a perfect half-wave plate to a good absorber for the left-handed circularly polarized light. This transformation leverages the intrinsic chirality with moderately high circular dichroism of ∼0.35 in both simulation and experimental observations, manifesting unprecedented control over the chiral light within sub-wavelength scales. Theoretical modeling and numerical simulations complement our experimental findings, offering deep insights into underlying mechanisms and the role of symmetry breaking in realizing chiral quasi-BICs. The observed phenomena open new pathways for developing ultra-compact chiral photonic devices with tailored optical properties, including highly sensitive chiral biosensors, circular dichroism spectroscopy, and chiral flat optical components for information processing.
Photonics Research
- Publication Date: Dec. 17, 2024
- Vol. 13, Issue 1, 69 (2025)
Positioning spherical nanoantennas with picometer precision|On the Cover
Haixiang Ma, Fu Feng, Jie Qiao, Jiaan Gan, and Xiaocong Yuan
Accurate positioning of nanoantennas is critical for their efficient excitation and integration. However, since nanoantennas are subwavelength nanoparticles, normally smaller than the diffraction limit, measuring their positions presents a significant challenge. This is particularly true for locating the nanoantenna along the z-direction, for which no suitable method currently exists. Here, we have theoretically developed and experimentally validated a novel light field capable of measuring the 3D positions of nanoantennas accurately. This field’s polarization chirality transitions from right-handed to left-handed along a predefined 3D direction at a subwavelength scale. For a spherical single-element nanoantenna, the polarization components of the scattering field change significantly as the nanoantenna moves, due to the rapid polarization transformation in the excitation light field. By analyzing the polarization components of the scattering field, we can achieve positional accuracy of the nanoantenna along the specified direction close to 20 pm. This work improves the accuracy of transversely distinguishing nanoantennas from 100 pm in conventional methods to 20 pm. Moreover, the positioning of the nanoantenna along three dimensions is all available as polarization transitions can be predefined along arbitrary 3D direction, which is significant for precision measurement and nanoscale optics. Accurate positioning of nanoantennas is critical for their efficient excitation and integration. However, since nanoantennas are subwavelength nanoparticles, normally smaller than the diffraction limit, measuring their positions presents a significant challenge. This is particularly true for locating the nanoantenna along the z-direction, for which no suitable method currently exists. Here, we have theoretically developed and experimentally validated a novel light field capable of measuring the 3D positions of nanoantennas accurately. This field’s polarization chirality transitions from right-handed to left-handed along a predefined 3D direction at a subwavelength scale. For a spherical single-element nanoantenna, the polarization components of the scattering field change significantly as the nanoantenna moves, due to the rapid polarization transformation in the excitation light field. By analyzing the polarization components of the scattering field, we can achieve positional accuracy of the nanoantenna along the specified direction close to 20 pm. This work improves the accuracy of transversely distinguishing nanoantennas from 100 pm in conventional methods to 20 pm. Moreover, the positioning of the nanoantenna along three dimensions is all available as polarization transitions can be predefined along arbitrary 3D direction, which is significant for precision measurement and nanoscale optics.
Photonics Research
- Publication Date: Dec. 16, 2024
- Vol. 13, Issue 1, 49 (2025)
Self-aligned dual-beam superresolution laser direct writing with a polarization-engineered depletion beam
Guoliang Chen, Dewei Mo, Jian Chen, and Qiwen Zhan
A fiber-based, self-aligned dual-beam laser direct writing system with a polarization-engineered depletion beam is designed, constructed, and tested. This system employs a vortex fiber to generate a donut-shaped, cylindrically polarized depletion beam while simultaneously allowing the fundamental mode excitation beam to pass through. This results in a co-axially self-aligned dual-beam source, enhancing stability and mitigating assembly complexities. The size of the central dark spot of the focused cylindrical vector depletion beam can be easily adjusted using a simple polarization rotation device. With a depletion wavelength of 532 nm and an excitation wavelength of 800 nm, the dual-beam laser direct writing system has demonstrated a single linewidth of 63 nm and a minimum line spacing of 173 nm. Further optimization of this system may pave the way for practical superresolution photolithography that surpasses the diffraction limit. A fiber-based, self-aligned dual-beam laser direct writing system with a polarization-engineered depletion beam is designed, constructed, and tested. This system employs a vortex fiber to generate a donut-shaped, cylindrically polarized depletion beam while simultaneously allowing the fundamental mode excitation beam to pass through. This results in a co-axially self-aligned dual-beam source, enhancing stability and mitigating assembly complexities. The size of the central dark spot of the focused cylindrical vector depletion beam can be easily adjusted using a simple polarization rotation device. With a depletion wavelength of 532 nm and an excitation wavelength of 800 nm, the dual-beam laser direct writing system has demonstrated a single linewidth of 63 nm and a minimum line spacing of 173 nm. Further optimization of this system may pave the way for practical superresolution photolithography that surpasses the diffraction limit.
Photonics Research
- Publication Date: May. 27, 2024
- Vol. 12, Issue 6, 1194 (2024)
Optical trapping-enhanced probes designed by a deep learning approach
Miao Peng, Guangzong Xiao, Xinlin Chen, Te Du, Tengfang Kuang, Xiang Han, Wei Xiong, Gangyi Zhu, Junbo Yang, Zhongqi Tan, Kaiyong Yang, and Hui Luo
Realizing optical trapping enhancement is crucial in biomedicine, fundamental physics, and precision measurement. Taking the metamaterials with artificially engineered permittivity as photonic force probes in optical tweezers will offer unprecedented opportunities for optical trap enhancement. However, it usually involves multi-parameter optimization and requires lengthy calculations; thereby few studies remain despite decades of research on optical tweezers. Here, we introduce a deep learning (DL) model to attack this problem. The DL model can efficiently predict the maximum axial optical stiffness of Si/Si3N4 (SSN) multilayer metamaterial nanoparticles and reduce the design duration by about one order of magnitude. We experimentally demonstrate that the designed SSN nanoparticles show more than twofold and fivefold improvement in the lateral (kx and ky) and the axial (kz) optical trap stiffness on the high refractive index amorphous TiO2 microsphere. Incorporating the DL model in optical manipulation systems will expedite the design and optimization processes, providing a means for developing various photonic force probes with specialized functional behaviors. Realizing optical trapping enhancement is crucial in biomedicine, fundamental physics, and precision measurement. Taking the metamaterials with artificially engineered permittivity as photonic force probes in optical tweezers will offer unprecedented opportunities for optical trap enhancement. However, it usually involves multi-parameter optimization and requires lengthy calculations; thereby few studies remain despite decades of research on optical tweezers. Here, we introduce a deep learning (DL) model to attack this problem. The DL model can efficiently predict the maximum axial optical stiffness of Si/Si3N4 (SSN) multilayer metamaterial nanoparticles and reduce the design duration by about one order of magnitude. We experimentally demonstrate that the designed SSN nanoparticles show more than twofold and fivefold improvement in the lateral (kx and ky) and the axial (kz) optical trap stiffness on the high refractive index amorphous TiO2 microsphere. Incorporating the DL model in optical manipulation systems will expedite the design and optimization processes, providing a means for developing various photonic force probes with specialized functional behaviors.
Photonics Research
- Publication Date: May. 01, 2024
- Vol. 12, Issue 5, 959 (2024)
Optical magnetic field enhancement using ultrafast azimuthally polarized laser beams and tailored metallic nanoantennas|Editors' Pick
Rodrigo Martín-Hernández, Lorenz Grünewald, Luis Sánchez-Tejerina, Luis Plaja, Enrique Conejero Jarque, Carlos Hernández-García, and Sebastian Mai
Structured light provides unique opportunities to spatially tailor the electromagnetic field of laser beams. These include the possibility of a sub-wavelength spatial separation of their electric and magnetic fields, which would allow isolating interactions of matter with pure magnetic (or electric) fields. This could be particularly interesting in molecular spectroscopy, as excitations due to electric and—usually very weak—magnetic transition dipole moments can be disentangled. In this work, we show that the use of tailored metallic nanoantennas drastically enhances the strength of the longitudinal magnetic field carried by an ultrafast azimuthally polarized beam (by a factor of ∼65), which is spatially separated from the electric field by the beam’s symmetry. Such enhancement is due to favorable phase-matching of the magnetic field induced by the electric current loops created in the antennas. Our particle-in-cell simulation results demonstrate that the interactions of moderately intense (∼1011 W/cm2) and ultrafast azimuthally polarized laser beams with conical, parabolic, Gaussian, or logarithmic metallic nanoantennas provide spatially isolated magnetic field pulses of several tens of Tesla. Structured light provides unique opportunities to spatially tailor the electromagnetic field of laser beams. These include the possibility of a sub-wavelength spatial separation of their electric and magnetic fields, which would allow isolating interactions of matter with pure magnetic (or electric) fields. This could be particularly interesting in molecular spectroscopy, as excitations due to electric and—usually very weak—magnetic transition dipole moments can be disentangled. In this work, we show that the use of tailored metallic nanoantennas drastically enhances the strength of the longitudinal magnetic field carried by an ultrafast azimuthally polarized beam (by a factor of ∼65), which is spatially separated from the electric field by the beam’s symmetry. Such enhancement is due to favorable phase-matching of the magnetic field induced by the electric current loops created in the antennas. Our particle-in-cell simulation results demonstrate that the interactions of moderately intense (∼1011 W/cm2) and ultrafast azimuthally polarized laser beams with conical, parabolic, Gaussian, or logarithmic metallic nanoantennas provide spatially isolated magnetic field pulses of several tens of Tesla.
Photonics Research
- Publication Date: May. 01, 2024
- Vol. 12, Issue 5, 1078 (2024)
Strong light–matter interactions based on excitons and the abnormal all-dielectric anapole mode with both large field enhancement and low loss
Yan-Hui Deng, Yu-Wei Lu, Hou-Jiao Zhang, Zhong-Hong Shi, Zhang-Kai Zhou, and Xue-Hua Wang
The room temperature strong coupling between the photonic modes of micro/nanocavities and quantum emitters (QEs) can bring about promising advantages for fundamental and applied physics. Improving the electric fields (EFs) by using plasmonic modes and reducing their losses by applying dielectric nanocavities are widely employed approaches to achieve room temperature strong coupling. However, ideal photonic modes with both large EFs and low loss have been lacking. Herein, we propose the abnormal anapole mode (AAM), showing both a strong EF enhancement of ∼70-fold (comparable to plasmonic modes) and a low loss of 34 meV, which is much smaller than previous records of isolated all-dielectric nanocavities. Besides realizing strong coupling, we further show that by replacing the normal anapole mode with the AAM, the lasing threshold of the AAM-coupled QEs can be reduced by one order of magnitude, implying a vital step toward on-chip integration of nanophotonic devices. The room temperature strong coupling between the photonic modes of micro/nanocavities and quantum emitters (QEs) can bring about promising advantages for fundamental and applied physics. Improving the electric fields (EFs) by using plasmonic modes and reducing their losses by applying dielectric nanocavities are widely employed approaches to achieve room temperature strong coupling. However, ideal photonic modes with both large EFs and low loss have been lacking. Herein, we propose the abnormal anapole mode (AAM), showing both a strong EF enhancement of ∼70-fold (comparable to plasmonic modes) and a low loss of 34 meV, which is much smaller than previous records of isolated all-dielectric nanocavities. Besides realizing strong coupling, we further show that by replacing the normal anapole mode with the AAM, the lasing threshold of the AAM-coupled QEs can be reduced by one order of magnitude, implying a vital step toward on-chip integration of nanophotonic devices.
Photonics Research
- Publication Date: Apr. 01, 2024
- Vol. 12, Issue 4, 854 (2024)
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