双模腔场中具有不同耦合常数的两原子多光子辐射谱

研究了与双模腔场具有不同耦合常数的两个二能级原子的多光子辐射谱,给出了双模多光子辐射谱的一般表达式.结果表明,当双模腔场分别处于不同数态时,虽然两原子与双模腔场之间具有不同的耦合常数,但对于任意的N₁和N₂(N_i(i＝1,2,)为模i腔场被每个原子吸收或发射的光子数),辐射谱总是关于共振频率ω₀对称分布;并且,当N₁＝N₂时,对于任意的数态光子数n₁和n₂交换,辐射谱不变.上述特点用解析方法给予了解释.计算了非简并双光子情况下的辐射谱,并得到了一些新结果.双模腔场中单原子及具有相同耦合常数的两原子辐射谱可从本文结果分别做为特例而得到.     

增加光子对和减少光子对相干态的统计性质

引入增加光子对相干态|ζ,q;m >_a=a^+m|ζ,q >和减少光子对相干态|ζ,q;-m >_b=b^m|ζ,q >,研究了这些态所描写的光场的统计性质。结果显示当在对相干态的a模增加光子时,两模的平均光子数均增加,亚泊松分布性质增强;当在对相干态的b模取走光子时,b模的平均光子数减少,而a模的平均光子数却增加;b模的亚泊松分布性质减弱,而a模的亚泊松分布性质却增强。我们还计算了场模间的相关度和场模的压缩。     

k光子Jaynes-Cummings模型的亚Poisson光子统计特性研究

本文利用量子电动力学理论,首次对 k 光子 Jaynes-Cummings 模型中单模激光场的稳态亚 Poisson 光子统计性质进行了系统研究.结果表明:在一般情况下,激光上能级相对泵浦参量 x_a 具有一个确定的阈值 x_at;当 x_a>x_at时,光场呈现亚 Poisson 光子统计;当 x_a>>x_at时,光场呈现出深度且完全恒定的亚 Poisson 光子统计.在特殊情况下,阈值 x_at-0,这时在激光腔内将直接诱发亚 Poisson 光子统计.随着 k(k≥2)值增加,阈值 x_at降低,光场亚 Poisson 光子统计程度增强.     

一种具有大带隙的各向异性二维光子晶体结构

提出一种新型各向异性材料(碲)二维光子晶体结构,应用有限时域差分法,对该结构特性进行数值分析,结果表明:通过优化结构参量,该结构具有较大的绝对光子禁带,禁带宽度为0.064ω_e(ω_e=2πc/a,a为晶格常量,c为光速),且该光子晶体的带隙具有很好的稳定性.     

调控电磁感应透明气体折射率实现可控光子带隙结构

提出了电磁感应透明(EIT)介质的一个新的相干操纵应用：控制电磁感应透明气体折射率实现可控光子带隙结构. 将一定密度的EIT原子气体充入以砷化钾为背景的椭圆孔柱中，计算表明该三角晶格排列椭圆柱光子晶体的光子带隙随外控制场而变. 通过调控自发辐射率、无辐射衰变率、控制光Rabi频率、原子数密度等外参数以及椭圆结构几何参数，在高频率区域得到了大小约0.0503ω_e(ω_e=2πc/a)的完全光子带隙.     

半导体中多光子吸收跃迁速率的全量子理论分析

本文从非线性光学中辐射跃迁速率的表达式出发,在全量子理论下,导出了半导体中任意阶多光子吸收跃迁速率的一般表达式。理论分析结果表明,n光子吸收跃迁速率与光强的n次方和n阶光子相干度成正比。本文在多能带及二能带理论模型下,对多光子吸收跃迁速率的一般表达式进行了化简,并对非线性相互作用项对跃迁速率的贡献,作了讨论。     

叠加激发双模压缩真空态的量子统计特性(英文)

从激发双模压缩真空态a^+mb^+m|ξ>出发构造了叠加态|Ψ>,研究了|Ψ>的量子统计特性.结果表明:在一定的条件下,随着相位差的变化,叠加态|Ψ>的平均光子数出现类似于Rabi振荡的崩塌与复原现象,而且与单个激发双模压缩真空态a^+mb^+m|ξ>相比,在叠加态|Ψ>中光场的相位压缩和亚泊松光子统计特性都得到了加强.     

增加光子位移福克态的量子统计性质

引入了增加光子位移福克态 a^+m| α,n〉,其中 | α,n〉是位移福克态,m是整数.用数值计算的方法研究了这种态的量子统计性质.结果表明,在位移福克态上增加光子后可以使原有的光场呈现较强的压缩,并能使光场的亚泊松特性得到明显增强.     

二维光子晶体耦合腔阵列的慢波效应研究

设计了一种六角晶格二维光子晶体耦合腔阵列，平面波展开法计算能带表明，处于禁带中的耦合缺陷腔模的色散曲线在光子晶体平面内所有k矢量方向更加平坦.模拟了横电波沿ΓK方向的透射谱.与光子晶体单缺陷腔相比，耦合腔阵列结构的缺陷腔模透射率提高三个量级以上，而群速度降低一个量级，得到0.007c的结果.该慢波效应在构造微型可调谐光延迟器和低阈值光子晶体激光器等方面具有潜在的应用前景.     

激光调Q CAI

从激光调Q速率方程出发,分析推导了激光调Q过程中,腔内光子数与工作物质内反转粒子数间的关系.再根据激光调Q的过程中,对腔Q值控制方式不同,将激光调Q技术分为:转镜调Q、声光调Q、电光调Q、饱和吸收调Q和脉冲透射式调Q.用C语言进行了激光调Q CAI软件的开发研制,获得了将文学、图形、动画和计算融为一体的,直观而生动地将调Q的理论和过程再现于屏幕的CAI课件.介绍了课件的内容、结构及其特点.     

基于线偏振光反射率测量介质折射率的研究

研究线偏振光的振幅反射率与介质折射率的关系,提出一种测量介质材料折射率的方法。文中从菲涅耳公式出发,推导出各向同性介质的线偏振光反射率与折射率的关系式,给出基于线偏振光反射率测定介质折射率的原理。设计实验方案,在不同入射角情况,定出线偏振光p方向和s方向两种线偏振光在玻璃表面的反射率,得到线偏振光振幅反射率随入射角变化的实验曲线。依此实验数据得出材料的折射率。结果表明,测出的介质材料的折射率与理论值相符,所采取的测定方案可行。     

Omni directional reflectance properties of superconductor-dielectric photonic crystal

The omnidirectional reflection properties in one dimensional superconductor-dielectric photonic crystal have been studied theoretically. In this present communication, the superconductor-dielectric photonic crystal in one dimension having alternate regions of superconductor-dielectric. The reflectance behaviors from these periodic multilayered structures are calculated for different angles of incidence. The reflectance and band structure is obtained by solving a Maxwell's equation using a translational matrix method. The study of reflectance bands of such superconductor-dielectric photonic crystal show that it can be used as broad band reflector.     

Angular tuning of defect modes spectrum in the one-dimensional photonic crystal with liquid-crystal layer

A one-dimensional ZrO₂/SiO₂ photonic crystal with a 4-n -pentyl-4' -cyanobiphenyl (5CB) nematic defect layer was used to investigate the transmission spectra of light polarized parallel and perpendicular to the liquid-crystal director at different angles of incidence. The spectra of the photonic crystal were shown to split into four polarized components T_ij at oblique incidence. When the incident angle increased, the bandgap edges and the defect modes shifted towards short wavelengths, while the amplitudes of the defect modes increased for the transverse magnetic polarization and decreased for the transverse electric polarization. The observed discrepancy between the defect mode amplitudes in the center and near the edges of the photonic bandgap was found to be related to the radiation losses inside the defect layer of a non-ideal photonic crystal. The simulated transmission spectra obtained using recurrence relations and taking into account the decay of defect modes are in good agreement with the experimental data.     

一维光子晶体的带隙分析

本文用转移矩阵法推导出一维光子晶体的禁带存在的判据;讨论了在光线正入射时,光子禁带存在的条件及特性.     

Anisotropy of light propagation in thin opal films

Thin opal films are prepared by crystallization in a moving meniscus, and their optical transmission spectra are recorded in polarized light and studied. It is shown that the anisotropy of light propagation in the films is unambiguously related to the photonic band structure of opal and depends on the angle of incidence, the orientation of the incidence plane with respect to the opal lattice, and the wavelength and polarization of the incident light. Azimuthal diagrams of transmitted polarized light are constructed in the range of photonic band gaps of three orders for oblique incidence of a light beam. The anisotropy is found to vary with the light wave-length independently in perpendicular polarizations. A model of the band structure of opal wherein opal is represented as an fcc lattice of close-packed spheres adequately describes the optical transmission of opal films only in the range of the first-order photonic band gap.     

基于光子晶体异质结的高效太阳能电池反射器研究

设计了一种可用于太阳能电池反射器的二维三角晶格光子晶体异质结结构.采用传输矩阵法对该结构在可见至近红外波长范围入射电磁波的反射率进行了模拟计算,并比较了不同入射方向下反射率的变化.结果表明,光线垂直入射时,该结构光子晶体对近红外波段入射光可实现完全反射|随着偏转角度的增大,在整个可见-近红外波段均显示出极高的反射特性.该结构有望用于制作覆盖整个可见光-近红外波段的高效全方位反射器.     

表层厚度渐变一维耦合腔光子晶体的反射相位特性及其应用

利用传输矩阵法研究了表层厚度渐变的一维非对称耦合腔光子晶体的反射相位特性. 研究表明, 光子禁带内(包括缺陷模附近)的反射率在98%以上, 且基本不受表层厚度影响, 特别是, 在非正入射情况下, 简并的缺陷模随着表层厚度的变化会发生分裂; 进一步研究发现, 在缺陷模分裂处附近, TE, TM偏振的反射相位以及它们之间的相位差均敏感地依赖于表层厚度的变化, 从而使得反射光的偏振态也随表层厚度的变化而敏感变化, 其物理机理在于缺陷模分裂所造成的剧烈相位变化. 基于上述特性, 设计了一种表层厚度呈二维周期变化的一维光子晶体结构, 从该结构反射的激光经透镜聚焦后, 在聚焦区域同时存在各种偏振态(包括沿不同方向的线偏振、左旋或右旋圆偏振、椭圆偏振等)的子光束, 它们叠加后在聚焦区域将产生具有无规相位和无规偏振态的光场. 以上结果能有效降低激光的相干性, 在激光核聚变等领域有潜在的应用价值.     

Chiral photonic crystals with an anisotropic defect layer: Oblique incidence

In the present paper we consider some properties of defect modes in chiral photonic crystals with an anisotropic defect layer at oblique light incidence. The problem is solved by Ambartsumian’s layer addition method. We investigated some peculiarities of the discussed system’s reflection spectra of the oblique light incidence for both the minimum and essential influences of the dielectric boundaries. Then we investigated some particulars of the density of photonic states spectra. We also discussed some peculiarities of the light energy distribution in the system. We found out that at large incidence angles two defect modes arise in the two regions of the selective reflection, each in one respectively, meanwhile, none arises in the central region of the complete reflection. Our investigations show that it is possible to rather widely change the emission peak wavelength in the subject system doped with some laser dye, by changing the incidence angle.     

Zero permittivity band characteristics in one-dimensional plasma dielectric photonic crystal

We consider the oblique propagation of electromagnetic waves in one-dimensional plasma dielectric photonic crystals, the superlattice structure consisting of alternating plasma and dielectric materials using transfer matrix method. Our results show that photonic band gaps for all polarizations can be obtained in one-dimensional plasma dielectric photonic crystals. These structures can exhibit a new type of band or gap, for the incidence angles other than normal incidence, near frequencies where the electric permittivity of the plasma layer changes sign. This new band or gap arises, from the dispersive properties of the plasma layer, only for TM polarized waves and its width increases with the increasing angle of incidence. This differential behaviour under polarization can be utilized in the design of an efficient polarization splitter. The band characteristic is affected by the plasma width, the plasma density, dielectric width, the dielectric constant of the dielectric medium and angle of incidence.     

一维光子晶体带隙结构研究

在考虑介质色散的基础上,研究了介质层厚度对光子晶体带隙结构的影响.利用传输矩阵法,计算了以LiF和Si两种材料组成的一维光子晶体带隙结构.结果表明,介质层厚度的增加会引起禁带的红移,厚度减小会引起蓝移.分析了含空气缺陷层、金属缺陷层的光子晶体结构,发现空气缺陷层对带隙结构的高反射区域变化不大,而在低反射区域,反射系数为零的波带之间出现了两边反射系数增加,中间反射系数减小的情况.在金属缺陷层的带隙结构中,金属对整个波长范围光的吸收作用不同,金属对低反射区1.6 μm、1.85 μm处透射率较大的透射光吸收作用明显,而在1.28~1.38 μm处透射率波长区间,几乎无吸收.