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Physical Optics|60 Article(s)
Generation of cylindrical optical lattices: from shape-invariant to propagation-invariant
Huiqing Li, Yile Shi, Yongsheng Dong, Yefeng Liu, Bo Zhang, and Zhijun Ren
Propagation-invariant beams have attracted major attention and presented applications in research areas such as particle acceleration, optical tweezers, and optical coherence tomography. On the basis of the introduced radial cosine phase gratings with high diffraction efficiency, this study observes a kind of novel shape-invariant radial lattice by assessing its Fresnel diffraction. Then, on the stationary phase principle, we originally construct and experimentally generate a family of new propagation-invariant (non-diffracting) radial lattices with polar symmetry. Their optical structures, propagation characteristics, and distinctive phase characteristics are studied. This study has important value for applying it in scientific fields in the future given that lattices have offered many applications, including optical communication in free space, quantum computation, quantum phase transition, spin–exchange interaction, and realization of magnetic fields. Propagation-invariant beams have attracted major attention and presented applications in research areas such as particle acceleration, optical tweezers, and optical coherence tomography. On the basis of the introduced radial cosine phase gratings with high diffraction efficiency, this study observes a kind of novel shape-invariant radial lattice by assessing its Fresnel diffraction. Then, on the stationary phase principle, we originally construct and experimentally generate a family of new propagation-invariant (non-diffracting) radial lattices with polar symmetry. Their optical structures, propagation characteristics, and distinctive phase characteristics are studied. This study has important value for applying it in scientific fields in the future given that lattices have offered many applications, including optical communication in free space, quantum computation, quantum phase transition, spin–exchange interaction, and realization of magnetic fields.
Chinese Optics Letters
- Publication Date: Jul. 31, 2025
- Vol. 23, Issue 8, 082601 (2025)
Generation and manipulation of multiple multidimensional perfect Poincaré beams enabled by a single-layer all-dielectric geometric metasurface
Ximin Tian, Shenglan Zhang, Yaning Xu, Junwei Xu, Yafeng Huang, Liang Li, Jielong Liu, Kun Xu, Xiaolong Ma, Linjie Fu, and Zhi-Yuan Li
Perfect Poincaré beams (PPBs) are highly esteemed for their topological charge-independent radius and intensity profile. However, the generation and manipulation of PPBs typically involve two-dimensional planes perpendicular to the optical axis, hindering broader usability. Here, leveraging a single-layer all-dielectric geometric metasurface platform, we numerically showcase the generation and manipulation of multiple multidimensional PPBs. Multiple dimensions of PPBs, involving orbital angular momentum (OAM), polarization state, and three-dimensional (3D) spatial propagation, can be manipulated independently via tailoring topological charges assigned to two orthogonal perfect vortex beam (PVB) components, varying initial phase difference and amplitude ratios between two orthogonal PVB components, and strategizing 3D propagation trajectories. To demonstrate the feasibility of the recipe, two metasurfaces are designed: one is for generating an array of PPBs with tailored polarization states along cylindrical helical trajectories, and the other is for creating dual arrays of PPBs with personalized OAM and polarization eigenstates across two misaligned focal planes. As a proof-of-concept illustration, we showcase an optical information encryption scheme through a single metasurface encoding personalized polarization states and OAM in parallel channels of multiple PPBs. This work endeavors to establish an ultra-compact platform for generating and manipulating multiple PPBs, potentially advancing their applications in optical encryption, particle manipulation, and quantum optics. Perfect Poincaré beams (PPBs) are highly esteemed for their topological charge-independent radius and intensity profile. However, the generation and manipulation of PPBs typically involve two-dimensional planes perpendicular to the optical axis, hindering broader usability. Here, leveraging a single-layer all-dielectric geometric metasurface platform, we numerically showcase the generation and manipulation of multiple multidimensional PPBs. Multiple dimensions of PPBs, involving orbital angular momentum (OAM), polarization state, and three-dimensional (3D) spatial propagation, can be manipulated independently via tailoring topological charges assigned to two orthogonal perfect vortex beam (PVB) components, varying initial phase difference and amplitude ratios between two orthogonal PVB components, and strategizing 3D propagation trajectories. To demonstrate the feasibility of the recipe, two metasurfaces are designed: one is for generating an array of PPBs with tailored polarization states along cylindrical helical trajectories, and the other is for creating dual arrays of PPBs with personalized OAM and polarization eigenstates across two misaligned focal planes. As a proof-of-concept illustration, we showcase an optical information encryption scheme through a single metasurface encoding personalized polarization states and OAM in parallel channels of multiple PPBs. This work endeavors to establish an ultra-compact platform for generating and manipulating multiple PPBs, potentially advancing their applications in optical encryption, particle manipulation, and quantum optics.
Chinese Optics Letters
- Publication Date: May. 22, 2025
- Vol. 23, Issue 6, 062601 (2025)
Optical isolator in a ferromagnetic microsphere coupled integrated Si3N4 waveguide
Hongyi Qiao, Shuai Wan, Guanting Xu, Zhen Shen, Guangcan Guo, Shuiming Hu, and Chunhua Dong
We experimentally demonstrate an optical isolator utilizing high-quality-factor whispering gallery modes in a yttrium iron garnet (YIG) microsphere, coupled with an integrated Si3N4 waveguide. By applying a magnetic field in the vertical direction of the resonator equator, we achieve the breaking of degeneracy between the clockwise (CW) and counterclockwise (CCW) modes, driven by photonic spin–orbit coupling (SOC) and the Faraday effect. The maximum wavelength separation observed is about 7.9 pm, comparable with the linewidth of the mode. The better effect of the refractive index matching between the YIG microsphere and the Si3N4 waveguide enables an isolation ratio of 16.9 dB under the critical coupling condition. This work presents a novel integrated approach for realizing non-reciprocity in photonic circuits, advancing the development of compact high-performance photonic devices. We experimentally demonstrate an optical isolator utilizing high-quality-factor whispering gallery modes in a yttrium iron garnet (YIG) microsphere, coupled with an integrated Si3N4 waveguide. By applying a magnetic field in the vertical direction of the resonator equator, we achieve the breaking of degeneracy between the clockwise (CW) and counterclockwise (CCW) modes, driven by photonic spin–orbit coupling (SOC) and the Faraday effect. The maximum wavelength separation observed is about 7.9 pm, comparable with the linewidth of the mode. The better effect of the refractive index matching between the YIG microsphere and the Si3N4 waveguide enables an isolation ratio of 16.9 dB under the critical coupling condition. This work presents a novel integrated approach for realizing non-reciprocity in photonic circuits, advancing the development of compact high-performance photonic devices.
Chinese Optics Letters
- Publication Date: Apr. 30, 2025
- Vol. 23, Issue 5, 052601 (2025)
Optical microcavity gyroscope assisted by mechanical modes in exceptional surfaces
Ranran Xie, Xueqing Cui, Zhuoqun Wang, Ruyi Xia, Yuechen Jia, and Feng Chen
Optical gyroscopes in microcavity platforms have attracted much attention for their vast applications. For Sagnac effect enhancement, the exceptional surface (ES) concept holds the potential to stabilize exceptional points (EPs), allowing for EP splitting amplification and robustness in sensors. We propose a new optical microcavity gyroscope near the ES. Under the mechanical mode assistance, theoretical analysis reveals its prominent advantages compared with conventional gyroscopes, especially achieving higher levels for extremely low rotational speeds. This breakthrough opens possibilities in high-precision angular velocity measurement, facilitating the development of more accurate and stable sensor technologies. Optical gyroscopes in microcavity platforms have attracted much attention for their vast applications. For Sagnac effect enhancement, the exceptional surface (ES) concept holds the potential to stabilize exceptional points (EPs), allowing for EP splitting amplification and robustness in sensors. We propose a new optical microcavity gyroscope near the ES. Under the mechanical mode assistance, theoretical analysis reveals its prominent advantages compared with conventional gyroscopes, especially achieving higher levels for extremely low rotational speeds. This breakthrough opens possibilities in high-precision angular velocity measurement, facilitating the development of more accurate and stable sensor technologies.
Chinese Optics Letters
- Publication Date: Mar. 20, 2025
- Vol. 23, Issue 3, 032601 (2025)
High robustness, billion Q packaged microcavity devices for soliton microcombs|Editors' Pick
Fangxing Zhang, Shengnan Huangfu, Shengqiang Ji, Yanjie Bai, Xuanyi Zhang, Zijing Cai, Tinglan Chen, Bo Ni, Bowen Ruan, and Jialüe Sun
The exceptional temporal and spatial photon confinement properties of whispering gallery mode (WGM) microcavities render them ideally suitable for nonlinear frequency conversion. Here, we present a reliable packaged microcavity device with vibration isolation, air tightness, temperature adaptability, and quality factors greater than 2 billion that can serve as a compact and stable platform for soliton optical comb generation. Low-noise soliton combs can be initiated with a repetition rate of 24.98 GHz at wavelengths near 1550 nm with 4 mW threshold power. Our work provides innovative solutions for investigating and manufacturing miniature, economical, and robust microcomb devices. The exceptional temporal and spatial photon confinement properties of whispering gallery mode (WGM) microcavities render them ideally suitable for nonlinear frequency conversion. Here, we present a reliable packaged microcavity device with vibration isolation, air tightness, temperature adaptability, and quality factors greater than 2 billion that can serve as a compact and stable platform for soliton optical comb generation. Low-noise soliton combs can be initiated with a repetition rate of 24.98 GHz at wavelengths near 1550 nm with 4 mW threshold power. Our work provides innovative solutions for investigating and manufacturing miniature, economical, and robust microcomb devices.
Chinese Optics Letters
- Publication Date: Feb. 19, 2025
- Vol. 23, Issue 2, 022601 (2025)
Tunable autofocus and unconventional OAM through dislocation in superimposed swallowtail vortex beams|On the Cover
Xiaoying Tang, Nana Liu, Shunyu Liu, Nan Wang, Shaozhou Jiang, Yuxuan Ren, Peilong Hong, and Yi Liang
Autofocusing beams are powerful photonic tools for manipulating micro/nanoparticles. Here, we propose a special type of dislocated-superimposed swallowtail vortex beam (DSVB) and analyze its propagation properties and optical manipulating capability. By modulating the parameters of the superposition number N and the topological charge l, DSVBs show asymmetric autofocusing propagation phenomena and unconventional orbital angular momentum (OAM), especially for opposite topological charges. Furthermore, when N = |l|, DSVBs form multiple solid focuses while preserving OAM during propagation, suggesting potential applications in multi-point trapping and rotational manipulation. These results deepen the understanding of autofocusing and OAM behaviors, highlighting DSVBs’ potential as photonic tools for optical manipulation. Autofocusing beams are powerful photonic tools for manipulating micro/nanoparticles. Here, we propose a special type of dislocated-superimposed swallowtail vortex beam (DSVB) and analyze its propagation properties and optical manipulating capability. By modulating the parameters of the superposition number N and the topological charge l, DSVBs show asymmetric autofocusing propagation phenomena and unconventional orbital angular momentum (OAM), especially for opposite topological charges. Furthermore, when N = |l|, DSVBs form multiple solid focuses while preserving OAM during propagation, suggesting potential applications in multi-point trapping and rotational manipulation. These results deepen the understanding of autofocusing and OAM behaviors, highlighting DSVBs’ potential as photonic tools for optical manipulation.
Chinese Optics Letters
- Publication Date: Sep. 08, 2025
- Vol. 23, Issue 10, 102602 (2025)
Three-dimensional abruptly autofocusing by counter-propagating airy pulses with a radial airy beam profile
Youngbin Park, Xiaolin Su, Qian Cao, and Andy Chong
We report the experimental observation of a three-dimensional abruptly autofocusing effect by synthesizing a radially distributed Airy beam with two counter-propagating Airy pulses in time. As the wave packet propagates in a dispersive medium, the radially distributed Airy beam converges inward to the center point. Two Airy pulses counter-propagate toward each other to merge to form a high-peak-power pulse. As a result, high intensity emerges abruptly as the wave packet achieves three-dimensional focusing. This autofocusing effect is believed to have potential applications such as material modification, plasma physics, and nanoparticle manipulations. We report the experimental observation of a three-dimensional abruptly autofocusing effect by synthesizing a radially distributed Airy beam with two counter-propagating Airy pulses in time. As the wave packet propagates in a dispersive medium, the radially distributed Airy beam converges inward to the center point. Two Airy pulses counter-propagate toward each other to merge to form a high-peak-power pulse. As a result, high intensity emerges abruptly as the wave packet achieves three-dimensional focusing. This autofocusing effect is believed to have potential applications such as material modification, plasma physics, and nanoparticle manipulations.
Chinese Optics Letters
- Publication Date: Sep. 16, 2025
- Vol. 23, Issue 10, 102601 (2025)
Enhanced reflection laser protection thin films compatible with visible light stealth
Zexiang He, Zexiong Hu, Jian Yang, Weijie Chen, Zhenzhen Duan, Ning Wang, Dan Wang, Xiaotan Ji, Nan Chen, Zhengqian Luo, and Yikun Bu
For bicolor regulation in laser protection compatible with visible light stealth, a metal–dielectric–enhanced reflection asymmetric Fabry–Perot structure is proposed that has high reflectance at the laser wavelength and the color control of the visible spectrum. The six-layer reflection enhancement unit is composed of an Al metal mirror, SiO2, Ta2O5, and an ultrathin Nb metal layer. The synergistic relationship between the background color and laser wavelength reflectance was analyzed and simulated. Six different colors from blue to red with high reflectance at 1064 nm laser wavelength up to 97.84% were prepared. The thin films can withstand 2535 W cm-2 power density continuous irradiation for 60 s without being destroyed. Moreover, a symmetrical structure presents the spectrum consistency from both directions, which makes the potential to be applied to the laser protective coatings. The blue symmetrical microreflector sample was prepared and sprayed on the nonplanar models to demonstrate the actual application effect. This simple and efficient scheme provides an innovative technical approach in the field of surface laser protection. For bicolor regulation in laser protection compatible with visible light stealth, a metal–dielectric–enhanced reflection asymmetric Fabry–Perot structure is proposed that has high reflectance at the laser wavelength and the color control of the visible spectrum. The six-layer reflection enhancement unit is composed of an Al metal mirror, SiO2, Ta2O5, and an ultrathin Nb metal layer. The synergistic relationship between the background color and laser wavelength reflectance was analyzed and simulated. Six different colors from blue to red with high reflectance at 1064 nm laser wavelength up to 97.84% were prepared. The thin films can withstand 2535 W cm-2 power density continuous irradiation for 60 s without being destroyed. Moreover, a symmetrical structure presents the spectrum consistency from both directions, which makes the potential to be applied to the laser protective coatings. The blue symmetrical microreflector sample was prepared and sprayed on the nonplanar models to demonstrate the actual application effect. This simple and efficient scheme provides an innovative technical approach in the field of surface laser protection.
Chinese Optics Letters
- Publication Date: Feb. 18, 2025
- Vol. 23, Issue 1, 012602 (2025)
White-light cavity and mode splitting effect in a three-turn lossy microfiber coil resonator
Feilin Zhang, Xiyuan Chen, Yulu Zhong, Qixuan Li, and Mengmeng Sha
Under a specified loss condition, the resonant mode in a three-turn lossy microfiber coil resonator exhibits periodic evolution among normal resonance, white-light cavity effect, and resonance mode splitting in response to alterations in the phase shift and coupling state. It exhibits normal resonance when the coupling state exceeds a threshold with specific loss. The white-light cavity effect is activated when the coupling state matches loss. The resonant phase bifurcates as the coupling state falls below the threshold. The excitation conditions for each resonant mode have been derived, and the critical coupling conditions exist for both normal resonance and mode splitting in the case of relatively small losses. Under a specified loss condition, the resonant mode in a three-turn lossy microfiber coil resonator exhibits periodic evolution among normal resonance, white-light cavity effect, and resonance mode splitting in response to alterations in the phase shift and coupling state. It exhibits normal resonance when the coupling state exceeds a threshold with specific loss. The white-light cavity effect is activated when the coupling state matches loss. The resonant phase bifurcates as the coupling state falls below the threshold. The excitation conditions for each resonant mode have been derived, and the critical coupling conditions exist for both normal resonance and mode splitting in the case of relatively small losses.
Chinese Optics Letters
- Publication Date: Feb. 04, 2025
- Vol. 23, Issue 1, 012601 (2025)
Wide-color-gamut, high-purity, and high-brightness thin film structural colors based on modified Fano resonant structure
Weijie Chen, Zexiang He, Zhenzhen Duan, Jian Yang, Ning Wang, Dan Wang, Zexiong Hu, Nan Chen, Zhengqian Luo, and Yikun Bu
Recently, the Fano resonance has played an increasingly important role in improving the color performance of structural colors. In this study, we further elucidate the asymmetric spectral shape generated by Fano resonance from a phase perspective and explore four distinct continuum state structures. By integrating the proposed cavity-like structure with a metal–dielectric–metal discrete state, multilayered thin-film structural colors with minimal background reflection, as low as 8%, were successfully achieved. The reflection peak of this structure exhibits a bandwidth of approximately 50 nm and reaches up to 80%, indicating heightened saturation and color brightness. Moreover, by adjusting the thickness, we effortlessly obtained a broader color gamut compared to Adobe RGB (45.2%), covering 56.7% of the CIE color space. Even adjusting a single layer can achieve a color gamut of 47.1%. In experiments, by deliberately choosing low oxygen-dependent materials, excellent RGB colors with high brightness and in high consistency with simulation results were successfully achieved. Therefore, the scheme’s simple process for structural color creation, along with its excellent color performance and the ability to effectively replicate simulation characteristics makes it highly valuable in fields like anticounterfeiting, decoration, display devices, and solar cell panels. Recently, the Fano resonance has played an increasingly important role in improving the color performance of structural colors. In this study, we further elucidate the asymmetric spectral shape generated by Fano resonance from a phase perspective and explore four distinct continuum state structures. By integrating the proposed cavity-like structure with a metal–dielectric–metal discrete state, multilayered thin-film structural colors with minimal background reflection, as low as 8%, were successfully achieved. The reflection peak of this structure exhibits a bandwidth of approximately 50 nm and reaches up to 80%, indicating heightened saturation and color brightness. Moreover, by adjusting the thickness, we effortlessly obtained a broader color gamut compared to Adobe RGB (45.2%), covering 56.7% of the CIE color space. Even adjusting a single layer can achieve a color gamut of 47.1%. In experiments, by deliberately choosing low oxygen-dependent materials, excellent RGB colors with high brightness and in high consistency with simulation results were successfully achieved. Therefore, the scheme’s simple process for structural color creation, along with its excellent color performance and the ability to effectively replicate simulation characteristics makes it highly valuable in fields like anticounterfeiting, decoration, display devices, and solar cell panels.
Chinese Optics Letters
- Publication Date: Aug. 21, 2024
- Vol. 22, Issue 8, 082601 (2024)
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