Interface states are widely applied in waveguide devices. However, previous studies failed to achieve photonic and phononic interface states independent of each other in the same crystal structure depending on the behavior of the crystal structure, i.e., photonic or phononic crystals, making the function of interface states single. In this study, straight-line and circular photonic and phononic interface states were realized independently in sunflower-type crystals. In addition, with a defect and a metal barrier, interface states could remain almost undamaged. The results have the potential to achieve multi-function devices and reduce the cost of engineering applications.interface states photonic and phononic crystals sunflower-type crystals
Chinese Optics Letters
2023, 21(6): 061301
In the fields of light manipulation and localization, quasiperiodic photonic crystals, or photonic quasicrystals (PQs), are causing an upsurge in research because of their rotational symmetry and long-range orientation of transverse lattice arrays, as they lack translational symmetry. It allows for the optimization of well-established light propagation properties and has introduced new guiding features. Therefore, as a class, quasiperiodic photonic crystal fibers, or photonic quasicrystal fibers (PQFs), are considered to add flexibility and richness to the optical properties of fibers and are expected to offer significant potential applications to optical fiber fields. In this review, the fundamental concept, working mechanisms, and invention history of PQFs are explained. Recent progress in optical property improvement and its novel applications in fields such as dispersion control, polarization-maintenance, supercontinuum generation, orbital angular momentum transmission, plasmon-based sensors and filters, and high nonlinearity and topological mode transmission, are then reviewed in detail. Bandgap-type air-guiding PQFs supporting low attenuation propagation and regulation of photonic density states of quasiperiodic cladding and in which light guidance is achieved by coherent Bragg scattering are also summarized. Finally, current challenges encountered in the guiding mechanisms and practical preparation techniques, as well as the prospects and research trends of PQFs, are also presented.photonic quasicrystal fiber guiding mechanism guiding features and applications challenges and prospects
Chinese Optics Letters
2023, 21(6): 060603
全球、区域及城市的碳浓度、碳源汇信息是应对气候变化、达成双碳目标、完善国际谈判、支持治理政策制定与执行的重要依据。国际认可的 “自上而下” 方法将卫星观测作为基础的通量计算技术, 是验证温室气体排放清单的重要手段。系统介绍了温室气体的卫星探测载荷原理、类别和发展, 以及反演、估算 CO 2 、CH 4 和 N 2 O 的浓度和排放通量的方法, 还有探测缺失和误差存在的影响因素等; 分析了对卫星探测温室气体能力提高的迫切需求, 浓度反演和排放量估算精度不足, 以及 N 2 O、氟化物等其他温室气体遥感研究缺乏、地基遥感验证能力薄弱等问题; 最后总结了我国温室气体卫星遥感技术的发展趋势, 主要是面向主被动高时空分辨率卫星的研制应用、高精度多尺度排放量估算 (特别针对城市、小区域和点源尺度)、氟化物遥感评估等主题, 以加强对碳排放的量化观测, 并增强对碳循环的理解, 提高感知和应对气候变化的能力。温室气体 卫星载荷 浓度 通量 反演 greenhouse gas satellite payload concentration flux retrieval
2022, 17(6): 581
High-Q metasurfaces have important applications in high-sensitivity sensing, low-threshold lasers, and nonlinear optics due to the strong local electromagnetic field enhancements. Although ultra-high-Q resonances of bound states in the continuum (BIC) metasurfaces have been rapidly developed in the optical regime, it is still a challenging task in the terahertz band for long years because of absorption loss of dielectric materials, design, and fabrication of nanostructures, and the need for high-signal-to-noise ratio and high-resolution spectral measurements. Here, a polarization-insensitive quasi-BIC resonance with a high-Q factor of 1049 in a terahertz all-silicon metasurface is experimentally achieved, exceeding the current highest record by 3 times of magnitude. And by using this ultra-high-Q metasurface, a terahertz intensity modulation with very low optical pump power is demonstrated. The proposed all-silicon metasurface can pave the way for the research and development of high-Q terahertz metasurfaces.
2022, 10(12): 2743
为了研究基于连续谱束缚态(BIC)高品质因子Q谐振, 提出了由双空心硅圆柱体组成太赫兹全介质超表面。采用数值模拟方法对结构的透射光谱及电磁场图进行了分析, 并利用本征模分析的方法研究了超表面结构参数对BIC频率的影响, 给出了该BIC超表面在太赫兹大频率范围工作的参数设计方法。结果表明, 在3.0THz左右实现了一个可调高Q环偶极Fano谐振; 本征模式的分析计算结果与入射电磁波模式的分析计算结果对称性不匹配,该超表面支持的是一个对称保护BIC。此研究为基于BIC的高Q超材料在超低阈值激光器件、非线性光学谐波产生及高灵敏度传感等领域的应用提供了理论参考。光学器件 连续谱束缚态 多极子分析 全介质超表面 高Q谐振 太赫兹 optical devices bound state in the continuum multipole analysis all-dielectric metasurface high-Q resonance terahertz
Anapole metamaterials have attracted growing attention in recent years due to their unique nonradiating and nontrivial properties. Although anapole modes have been demonstrated in metamaterials with three-dimensional structures, the design and realization of planar anapole metamaterials in a wide frequency range is still a big challenge. Here we propose and experimentally demonstrate a planar anapole metamaterial consisting of dumbbell-shaped apertures on a stainless-steel sheet at terahertz frequencies. The planar metamaterial can generate a resonant transparency in the terahertz spectrum due to the excitation of the anapole mode. Particularly, the frequency of anapole-induced resonant transparency can be tuned easily in the range of 0.15–0.93 THz by simply varying one geometric parameter of the dumbbell apertures. We anticipate that the resonant transparency in planar anapole metamaterials can be potentially used in filters, sensors, or other photonic devices.
2021, 9(2): 02000125
采用阴阳离子共掺法提高了溴化铈晶体质量。研究结果表明，通过掺杂F-能有效消除晶体开裂、潮解等缺陷，同时掺杂Sr2+能提高晶体的光学线性输出及能量分辨率。采用改进的坩埚下降法进行晶体生长，掺杂摩尔分数为x(CeBr3)=98%,x(SrBr2)=2%,x(CeF3)= 10% 时，生长出45 mm×90 mm的溴化铈晶体毛坯，切割成的器件经137Cs放射源662 keV γ线作用下能量分辨率可达4.0%。溴化铈 阴阳离子共掺 潮解 闪烁晶体 坩埚下降法 cerium bromide cationic and anionic co doping deliquescence scintillation crystal bridgman method