Author Affiliations
Abstract
Northwestern Polytechnical University, School of Physical Science and Technology, MOE Key Laboratory of Material Physics and Chemistry under Extraordinary Conditions, Key Laboratory of Light-Field Manipulation and Information Acquisition, Ministry of Industry and Information Technology, Shaanxi Key Laboratory of Optical Information Technology, Xi’an, China
Optical cavities play crucial roles in enhanced light–matter interaction, light control, and optical communications, but their dimensions are limited by the material property and operating wavelength. Ultrathin planar cavities are urgently in demand for large-area and integrated optical devices. However, extremely reducing the planar cavity dimension is a critical challenge, especially at telecommunication wavelengths. Herein, we demonstrate a type of ultrathin cavities based on large-area grown Bi2Te3 topological insulator (TI) nanofilms, which present distinct optical resonance in the near-infrared region. The result shows that the Bi2Te3 TI material presents ultrahigh refractive indices of >6 at telecommunication wavelengths. The cavity thickness can approach 1/20 of the resonance wavelength, superior to those of planar cavities based on conventional Si and Ge high refractive index materials. Moreover, we observed an analog of the electromagnetically induced transparency (EIT) effect at telecommunication wavelengths by depositing the cavity on a photonic crystal. The EIT-like behavior is derived from the destructive interference coupling between the nanocavity resonance and Tamm plasmons. The spectral response depends on the nanocavity thickness, whose adjustment enables the generation of obvious Fano resonance. The experiments agree well with the simulations. This work will open a new door for ultrathin cavities and applications of TI materials in light control and devices.
topological insulator optical nanocavity photonic crystal electromagnetically induced transparency-like effect Advanced Photonics
2024, 6(3): 036001
1 西北工业大学物理科学与技术学院光场调控与信息感知工业和信息化部重点实验室，陕西省光信息技术重点实验室，陕西 西安 710129
2 兰州理工大学理学院，甘肃 兰州 730050
本文研究了金属光栅表面等离激元与单层二硫化钨激子的耦合共振特性。利用时域有限差分法模拟了一维金光栅/单层二硫化钨混合结构的光谱响应及电场强度分布。结果表明，金光栅表面等离激元与单层二硫化钨激子耦合可产生光谱劈裂。当改变金光栅的结构参数时，混合结构的反射光谱出现了明显的反交叉现象。采用时域耦合模理论拟合了混合结构不同参数时的反射光谱，拟合结果与数值模拟符合较好。金光栅表面等离激元与单层二硫化钨激子的耦合作用满足强耦合判据。耦合振荡器模型分析结果表明，当金光栅周期为400 nm、宽度为300 nm时，混合结构强耦合光谱的拉比劈裂为54.6 meV，其与时域耦合模理论结果一致。该工作将为表面等离激元与激子强耦合作用的深入研究与器件开发开辟新途径。
表面等离激元 一维金光栅 二硫化钨 激子 强耦合
Author Affiliations
Abstract
1 Northwestern Polytechnical University, School of Physical Science and Technology, Key Laboratory of Light Field Manipulation and Information Acquisition, Ministry of Industry and Information Technology, Shaanxi Key Laboratory of Optical Information Technology, Xi’an, China, 710129
2 Nanjing University of Posts and Telecommunications, College of Electronic and Optical Engineering & College of Microelectronics, Nanjing, China, 210046
3 Aalto University, Department of Electronics and Nanoengineering and QTF Centre of Excellence, Aalto, Finland
Chirp-free solitons have been mainly achieved with anomalous-dispersion fiber lasers by the balance of dispersive and nonlinear effects, and the single-pulse energy is constrained within a relatively small range. Here, we report a class of chirp-free pulse in normal-dispersion erbium-doped fiber lasers, termed birefringence-managed soliton, in which the birefringence-related phase-matching effect dominates the soliton evolution. Controllable harmonic mode locking from 5 order to 85 order is obtained at the same pump level of ~10 mW with soliton energy fully tunable beyond ten times, which indicates a new birefringence-related soliton energy law, which fundamentally differs from the conventional soliton energy theorem. The unique transformation behavior between birefringence-managed solitons and dissipative solitons is directly visualized via the single-shot spectroscopy. The results demonstrate a novel approach of engineering fiber birefringence to create energy-tunable chirp-free solitons in normal-dispersion regime and open new research directions in fields of optical solitons, ultrafast lasers, and their applications.
Ultrafast Science
2022, 2(1): 9760631
Author Affiliations
Abstract
1 MOE Key Laboratory of Material Physics and Chemistry under Extraordinary Conditions, and Shaanxi Key Laboratory of Optical Information Technology, School of Physical Science and Technology, Northwestern Polytechnical University, Xi’an 710129, China
2 State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi’an 710119, China
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Metasurfaces, with extremely exotic capabilities to manipulate electromagnetic (EM) waves, have derived a plethora of advanced metadevices with intriguing functionalities. Tremendous endeavors have been mainly devoted to the static metasurfaces and metadevices, where the functionalities cannot be actively tuned in situ post-fabrication. Due to the intrinsic advantage of active tunability by external stimulus, graphene has been successively demonstrated as a favorable candidate to empower metasurfaces with remarkably dynamic tunability, and their recent advances are propelling the EM wave manipulations to a new height: from static to dynamic. Here, we review the recent progress on dynamic metasurfaces and metadevices enabled by graphene with the focus on electrically-controlled dynamic manipulation of the EM waves covering the mid-infrared, terahertz, and microwave regimes. The fundamentals of graphene, including basic material properties and plasmons, are first discussed. Then, graphene-empowered dynamic metasurfaces and metadevices are divided into two categories, i.e., metasurfaces with building blocks of structured graphene and hybrid metasurfaces integrated with graphene, and their recent advances in dynamic spectrum manipulation, wavefront shaping, polarization control, and frequency conversion in near/far fields and global/local ways are elaborated. In the end, we summarize the progress, outline the remaining challenges, and prospect the potential future developments.
metasurface dynamic metasurface graphene graphene plasmons light field manipulation electromagnetic wave manipulation Opto-Electronic Advances
2022, 5(4): 200098
1 北京师范大学核科学与技术学院射线束技术教育部重点实验室, 北京 100875
2 北京市科学技术研究院辐射技术研究所, 北京 100875
高能X射线微焦斑在高能微束X射线分析技术中具有重要应用。为了获得高能X射线微焦斑透镜,理论设计了基于锥形单毛细管的高能X射线微焦斑透镜,该类锥形毛细管透镜可以把能量为100 keV的X射线会聚成微焦斑,焦斑直径和功率密度增益分别在微米和几十量级,对应的焦距为5毫米左右;并且理论模拟了该类锥形毛细管透镜采用玻璃反射面和金属(纯金)反射面后的特性,在透镜焦斑处,采用纯金金属反射面的锥形毛细管透镜的光通量为采用普通硅酸盐玻璃反射面的锥形毛细管透镜的14.8倍。模拟结果对锥形单毛细管X射线透镜的研制和应用具有指导意义。
光学学报
2022, 42(11): 1134019
Author Affiliations
Abstract
MOE Key Laboratory of Material Physics and Chemistry under Extraordinary Conditions, Key Laboratory of Light-Field Manipulation and Information Acquisition, Ministry of Industry and Information Technology, and Shaanxi Key Laboratory of Optical Information Technology, School of Physical Science and Technology, Northwestern Polytechnical University, Xi’an 710129, China
We present the perfect light absorption of monolayer molybdenum disulfide () in a dielectric multilayer system with two different Bragg mirrors. The results show that the strong absorption of visible light in monolayer is attributed to the formation of optical Tamm states (OTSs) between two Bragg mirrors. The absorption spectrum is dependent on the layer thickness of Bragg mirrors, incident angle of light, and the period numbers of Bragg mirrors. Especially, the nearly perfect light absorption (99.4%) of monolayer can be achieved by choosing proper period numbers, which is well analyzed by the temporal coupled-mode theory.
optical Tamm states molybdenum disulfide light absorption Chinese Optics Letters
2021, 19(10): 103801
Author Affiliations
Abstract
1 Northwestern Polytechnical University, School of Physical Science and Technology, MOE Key Laboratory of Material Physics and Chemistry Under Extraordinary Conditions, and Shaanxi Key Laboratory of Optical Information Technology, Xi’an, China
2 Shenzhen University, Collaborative Innovation Centre for Optoelectronic Science and Technology, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Shenzhen, China
Cylindrical vector beams and vortex beams, two types of typical singular optical beams characterized by axially symmetric polarization and helical phase front, possess the unique focusing property and the ability of carrying orbital angular momentum. We discuss the formation mechanisms of such singular beams in few-mode fibers under the vortex basis and show recent advances in generating techniques that are mainly based on long-period fiber gratings, mode-selective couplers, offset-spliced fibers, and tapered fibers. The performances of cylindrical vector beams and vortex beams generated in fibers and fiber lasers are summarized and compared to give a comprehensive understanding of singular beams and to promote their practical applications.
cylindrical vector beam vortex beam orbital angular momentum two-mode fiber fiber laser beam shaping Advanced Photonics
2021, 3(1): 014002
西北工业大学理学院超常条件材料物理与化学教育部重点实验室与陕西省光信息技术重点实验室, 陕西 西安 710072
提出了一种增强石墨烯光吸收率的布拉格光栅/石墨烯/金属薄膜光学结构。运用传输矩阵和时域有限差分法研究了其光传输特性,发现布拉格光栅与金属薄膜之间形成的塔姆等离激元局域场可有效增强光与石墨烯的相互作用,单层石墨烯的近红外光吸收率约增大了36倍。探讨了布拉格光栅的周期、石墨烯位置、入射角度、布拉格光栅层厚度及石墨烯化学势与石墨烯光吸收的关系。研究结果表明,上述物理参数的变化可有效调控石墨烯的光吸收波长及效率。研究结果为高性能石墨烯探测器等新型光电子器件的实现提供了新的途径。
薄膜 光学薄膜 石墨烯 塔姆等离激元 光吸收
Author Affiliations
Abstract
MOE Key Laboratory of Material Physics and Chemistry under Extraordinary Conditions, and Shaanxi Key Laboratory of Optical Information Technology, School of Science, Northwestern Polytechnical University, Xi’an 710072, China
We demonstrate an all-fiber Q-switched cylindrical vector laser based on a black phosphorus saturable absorber and a transverse mode converter. The saturable absorber is prepared by incorporating the polyvinyl alcohol with anti-oxidized black phosphorus nanosheets exfoliated in aqueous poly(dimethyldiallyl ammonium chloride) solution. The mode converter is composed of a tapered two-mode fiber and a single-mode fiber, and it can excite switchable azimuthally and radially polarized beams by modulating the input polarization. By enhancing the pump power from 64.68 to 174.82 mW, the repetition rate of the Q-switched azimuthally/radially polarized laser enlarges from 16.72/19.25 to 30.71/37.82 kHz.
140.3540 Lasers, Q-switched 190.4400 Nonlinear optics, materials Chinese Optics Letters
2019, 17(2): 020004
对于远距离、大视场、多个运动目标的光电跟踪,现有光学系统形式难以同时兼顾大口径、大视场与高角分辨率的要求。通过模仿人眼小凹转动视觉生理机制,设计了一种轻型物方扫描校正镜组,具有中红外成像与激光测距的共口径同轴五反式新型光学系统。该光学系统主镜口径为1000 mm,瞬时扫描有效口径为600 mm,最大视场角达到20.7°,中波红外成像传感器像元角分辨率优于13 mrad,激光测距单元作用距离达到20 km。该新型光学系统具有大视场范围,可同时对6个以上远距离高速运动目标进行跟踪。
几何光学 反射式光学系统设计 同轴五反 小凹转动 三维成像 大视场 多目标
