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光子晶体是介电常数(折射率)随光波长大小周期性巨大变化的人工晶体。光子晶体的诞生使人类操控光子由梦想成为现实。光子晶体结构对置于光子晶体中的荧光客体自发辐射速率和荧光强度具有重要的调制作用。与半导体晶格对电子波函数的调制相类似,光子带隙材料能够调制具有相应波长的电磁波——当电磁波在光子带隙材料中传播时,由于存在布拉格散射而受到调制,电磁波能量形成能带结构。能带与能带之间出现带隙,即光子带隙。所具能量处在光子带隙内的光子,不能进入该晶体。本文将在综述这一领域国际上的重要研究进展基础上,重点介绍本课题组在镧系氧化物三维晶体的自组装与光子带隙对稀土离子自发辐射调制方面的研究成果。 相似文献
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为了研究基于旋磁材料的一维光子晶体一正一斜地放置串联结构的传输属性,利用适合旋磁材料一维层状结构的传输矩阵计算公式,计算了串联结构的透射谱。在对结构施加相同方向的外磁场时,得到窄带透射峰,实现了滤波功能。改变右侧光子晶体磁场方向,从左侧光子晶体入射的光束将在右侧斜放的光子晶体表面产生全反射,光束方向偏转90°。通过磁场方向的调制实现了器件的滤波和偏光双功能。 相似文献
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研究了动态各向同性光子晶体中二能级原子自发辐射的性质,主要讨论了光子晶体能带带边频率随时间作阶跃调制和三角函数周期调制两种情况下,原子上能级占据数随时间的演化特性.当光子晶体能带带边频率随时间作阶跃调制时,原子上能级占据数随时间的演化不仅和上能级与能带带边的相对位置δ有关,更依赖于阶跃调制发生的时刻.调制发生时刻不同,调制后原子上能级占据数随时间的演化也不同.当光子晶体能带带边频率随时间作三角函数周期调制时,二能级原子上能级占据数随时间作总体衰减的准周期振荡.通过选择调制频率和调制初相位可调控准周期振荡的频率、峰值与谷值的大小以及占据数的总体衰减速度等. 相似文献
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全光缓存器是未来全光网络中不可或缺的关键器件.针对可控光延迟和光存储的应用需求,研究了光子晶体波导中慢光传输的外部动态调制.设计了一种新型的聚合物光子晶体波导结构.用平面波展开法仿真得到该波导结构带隙中存在单一的TE导模,导模带边处的群速度可达10-2c.由于基底聚合物材料具有高电光系数和瞬态的电光响应时间,且导模慢光传输产生的电磁场局域对电光效应有增强作用.可在低涮制电压的条件下实现对慢光导模的大范围动态调制.数值分析得到在外加调制电压为80 V时导模带边波长的移动幅度达80.8 nm.慢光导模的移动随调制电压的变化基本呈线性关系,且调制的灵敏度约为1 nm/V.这种线性的外部动态调制基本可满足全光网络对慢光光缓存的需求. 相似文献
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本文提出一种采用石榴石型铁氧体磁性材料的太赫兹滤波器,利用波导线缺陷和腔内点缺陷的耦合特性,通过改变腔内介质柱半径及分布,实现对某个波长的耦合,达到了高效率滤波的功能;改变外磁场的大小,影响铁氧体材料的磁导率变化,使谐振频率发生改变,从而对THz波进行滤波.应用平面波展开法(PWM)和时域差分有限法(FDTD)进行仿真分析,研究结果表明,该滤波器其插入损耗为0.0997 d B,3 d B带宽为8.22 GHz,实现了低损耗窄带滤波. 相似文献
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Changzhi Li 《International Journal of Infrared and Millimeter Waves》2004,25(8):1245-1254
The photonic band structure, mode field distribution, and leakage loss of different photonic crystal fibers are studied by the full vectorial plane wave expansion method and an extended beam propagation method. A comparison on the waveguiding mechanism is conducted among solid-core triangular-lattice PCF, air-core honeycomb PCF, and solid-core honeycomb PCF. For the latter two structures, which conduct light by the photonic bandgap effect, the advantages of down-doped solid-core honeycomb structure are demonstrated for its Gaussian-like mode field distribution and low leakage loss. A combined study on the leakage loss and band structure of solid-core honeycomb PCF has revealed the distinctive properties of photonic bandgap effect. 相似文献
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The dispersive properties of three-dimensional magnetized plasma photonic crystals composed of homogeneous magnetized plasma spheres immersed in isotropic dielectric host with face-centered-cubic lattices are theoretically studied based on plane wave expansion method, as the magneto-optical Faraday effects of magnetized plasma are considered. The equations for calculating the band structures are theoretically deduced. The photonic band gap and a flatbands region can be obtained. The influences of host dielectric constant, plasma collision frequency, filling factor, external magnetic field and plasma frequency on the dispersive properties are investigated in detail, respectively, and some corresponding physical explanations are also given. The numerical results show that the photonic band gap can be manipulated by the plasma frequency, filling factor, external magnetic field and host dielectric constant, respectively. However, the plasma collision frequency has no effects on photonic band gap. The location of flatbands region cannot be tuned by any parameters except for the plasma frequency and external magnetic field. 相似文献
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本文研究了硅柱在MnFe2O4磁性液体背景中排列成六边形结构的二维光子晶体的可调谐负折射特性. 利用平面波展开法和时域有限差分法理论研究了硅柱-磁性液体体系二维光子晶体的带隙结构、等频曲线和负折射现象随外磁场强度的变化关系. 模拟结果表明, 硅柱-磁性液体体系二维光子晶体工作在TE模式时, 其负折射特性可由外磁场调节. 在固定背景溶液的磁性颗粒体积分数和入射光频率时, 所研究的折射光束的偏转角和光子晶体的负折射率绝对值随外磁场的增大而增大, 而在固定背景溶液的磁性颗粒体积分数和外磁场强度时, 负折射角和负折射率的绝对值随入射光归一化频率增大而减小. 固定外场强度和入射光频率时, 所研究结构的负折射特性随背景溶液的磁性颗粒体积分数增大而变弱. 相似文献
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光控二维光子晶体光开关 总被引:1,自引:0,他引:1
提出了一种调节液晶光子晶体光子带隙的方法。二维三角介质柱形光子晶体位于2块熔凝石英片之间,在介质柱之间填充各向同性排列的液晶,受偏振紫外光照射后,光诱导液晶分子定向排列,通过光诱导液晶分子取向改变液晶的折射率。数值模拟结果表明:通过外界光场控制所填充的向列相液晶分子的方向可以对这种二维三角形介质柱光子晶体的禁带结构进行调节。该可调光子晶体可控制波导中TM模和TE模的选择性传输,因而可应用于制作全光光开关。 相似文献
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石墨烯在光电子学领域具有广泛应用,但石墨烯的吸收率较低限制了其在某些方面的应用。为了改善单层石墨烯的吸收特性,在前人研究的基础上,设计了石墨烯和光子晶体异质结构构成的复合结构。利用4×4传输矩阵法研究了外磁场、费米能量和设计波长等参数对石墨烯吸收特性的影响。结果表明,所设计的光学结构使石墨烯既保持了原有的宽吸收带,还增加了数目可调的窄吸收带。由于考虑到磁光效应,石墨烯的吸收特性表现出一定的磁圆二色性。对于各吸收带,通常情况下左旋圆偏振光的吸收率要大于右旋圆偏振光的吸收率。但调节外磁场和费米能量,可使各吸收带具有99%以上的吸收,在一定的条件下,还可实现近完美的100%吸收。研究结果为光电子学领域中基于石墨烯的相关器件的设计提供了参考。 相似文献
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By probing the resonances between a photonic band and an external laser field and their nonlinear changes in angle-resolved reflectivity, we show experimental evidence that the nonlinear optical changes in a two-dimensional photonic crystal waveguide with a Kerr nonlinearity are critically dependent on the dispersion nature and the group velocity of the photonic bands. The results agree well with the behavior predicted from band structures, indicating that the design of nonlinear optical properties of material systems is realistically possible by band dispersion and group velocity engineering. 相似文献
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Band gap characteristics of plasma with periodically varying external magnetic field 总被引:1,自引:0,他引:1
The reflectance characteristics of a one-dimensional periodically magnetized plasma structure is studied by using the transfer matrix method. It is found that this system has the band gap characteristics of photonic crystals, so we also name it a plasma photonic crystal. The results show that the gap location and gap width can be controlled by the incident angle. If the external magnetic field is small, the gap location and gap width change significantly with incident angle, while they change only slightly when the external magnetic field is sufficiently large. The collision frequency has little effect on the gap location and gap width while it makes the amplitude of reflectance and transmission decrease. This new type of plasma photonic crystal could have potential applications in designing tunable photonic crystal devices. 相似文献
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The polariton propagation in one-dimensional photonic crystals and quasicrystals based on highly doped quantum-well structures has been theoretically studied. The superradiant and photonic crystal regimes have been considered and expressions for band gap edges for light waves in the Bragg structures have been obtained. The reflection and absorption spectra of such systems have been calculated and the so-called two-wave approximation to their study has been applied. The optical properties of the doped multiple-quantum-well structures are compared with those of undoped ones. 相似文献