Compact 1-D magnetophotonic crystals with simultaneous large magnetooptical Kerr rotation and high reflectance

We have investigated the case of reflection-type one-dimensional magnetophotonic crystals (MPCs) in order to achieve high reflectance and high magnetooptical Kerr effect, simultaneously, utilizing a low number of magnetic layers. In a MPC structure including only one Bi:YIG magnetic layer, we have achieved a Kerr rotation as huge as θ_k ≈ 90° with a reflectance of R > 97%. In addition, we have introduced a thinner structure having three Bi:YIG layers and with approximately the same Kerr rotation and reflectance. Both the structures are very compact with lengths of less than 9 μm.     

Defect modes and magnetooptical activity of a one-dimensional magnetophotonic crystal

The reflection spectrum of a periodic transverse-magnetized structure containing a finite number of ferromagnet-dielectric periods has been obtained. The influence of a substitutional defect on the reflection spectrum is analyzed for normal incidence of light on the structure. It is shown that the intensity and position of the defect miniband in the bad gap of the spectrum depend on the location of the defect layer in the structure and on its type (magnetic or nonmagnetic). It is found that magnetooptical activity of the defect structure is higher than in a defect-free structure.     

带缺陷结构的二维磁性光子晶体的数值模拟分析

利用频域有限差分方法分析了多种带缺陷结构二维磁性光子晶体（二重对称,四重对称和六重对称结构）的法拉第旋转角与椭圆率的变化特性.结果表明：在这些结构中,光波均被局域在中心缺陷处;同时,对于具有四重对称轴结构的材料,在其法拉第旋转角增加的同时,出射光波的椭圆率没有明显的增加;但对于不具有四重对称轴结构的材料,其法拉第旋转角增加的同时,出射光波的椭圆率也在增加.因此,只有在具有四重对称轴结构的二维磁性光子晶体中引入缺陷,才能很好地抑制光波偏振态的变化.这种带缺陷的二维磁性光子晶体结构有可能用于制作磁性光子晶体光 关键词： 磁光效应 二维磁性光子晶体 缺陷 频域有限差分法     

磁光光子晶体结构的法拉第效应增强

在超薄薄膜的基础上,基于时域有限差分法原理,利用FDTD Solutions仿真软件分别研究了基于两种多层膜结构和一种金属光栅结构的磁光光子晶体法拉第旋光效应。研究表明,多层膜结构的法拉第旋光效应增强原理为入射光在薄膜中心层的透射谱谐振,而金属光栅周期结构的法拉第效应增强是通过金属光栅激发表面等离子体实现的;在三种结构中,金属光栅周期结构具有更广的法拉第偏转角增强域。进一步通过参数优化,实现对金属光栅周期结构工作波长的可调节性研究,为薄膜型磁光器件设计提供了理论依据。     

Nonlinear magneto-optical effects in all-garnet magnetophotonic crystals

Nonlinear magneto-optical properties of all-garnet magnetophotonic crystals composed of alternating layers of ferromagnetic Bi₃Fe₅O₁₂ (BIG) and Sm₃Ga₅O₁₂ quarter-wavelength layers with a half-wavelength BIG microcavity mode are presented. The samples are grown by rf-magnetron sputtering on non-magnetic GGG substrate. Many-fold enhancement of the magnetization-induced effects in second-harmonic generation (SHG) as compared with linear magneto-optical effects are observed: the SHG magnetic contrast up to 50% and magnetization-induced rotation of the polarization plane of about 90° are measured at the resonance microcavity wavelengh of λ=779 nm.     

High performance reflection-type 1D magnetophotonic crystals with flat-top responses

In this paper, a theoretical study on the case of reflection-type one-dimensional magnetophotonic crystals (MPCs) has been carried out to establish high performance structures having concurrent high reflectance and large Kerr rotation with flat-top responses. The introduced MPCs are able to maintain their flat-top responses in a wide range of incident angle. For practical purposes, we have also inquired the influence of the error in the thickness of individual layers on the operational parameters of the MPCs. The reflectance flatness and bandwidth of the MPCs are appreciably stable against the imposed thickness errors.     

Enhancement of the magnetorefractive effect in magnetophotonic crystals

The magnetorefractive effect in a one-dimensional magnetophotonic crystal, more specifically, a photonic crystal (SiO₂/Ta₂O₅) containing a built-in defect in the form of a thin layer of the Co-(Al-O) magnetic nanocomposite, is studied in a computer simulation experiment. The structure of the unit cell of the photonic crystal in which most of the field energy is concentrated in cells nearest to the defect is determined. This makes it possible to increase the defect-mode Q factor and, owing to the multiple passage of light along the defect, to enhance the magnetorefractive effect by more than one order of magnitude as compared to a thin film on a substrate and by two orders of magnitude as compared to thick films. The reflectance of these structures in an applied magnetic field can be as high as 60%.     

Magneto-optical properties of one-dimensional conjugated magnetophotonic crystals heterojunctions

The 4 × 4 transfer matrix for the magneto-optical layer at oblique incidence is derived. With the help of the transfer matrix, the magneto-optical properties of one-dimensional conjugated magnetophotonic crystals (MPC) heterojunctions are studied. The results show that there exists a Tamm state localized at the interface between conjugated MPC. By coupling the Tamm states, high transmittance and large Faraday rotation angle can be obtained simultaneously in conjugated MPC multiple heterojunctions structure. It can be used to make novel mageto-optical device, promised to further application in optical information process.     

双层光子晶体氮化镓蓝光发光二极管结构优化的研究

为了提升氮化镓(GaN)蓝光发光二极管(LED)光提取效率, 设计了双层光子晶体LED模型. 提出等效折射率近似方法, 简化求解了结构中的介质波导模式分布. 从而对模型中顶层光子晶体刻蚀深度d, 嵌入式光子晶体厚度T及其距有源层距离D等结构参数进行了优化. 同时利用时域有限差分方法对优化结果进行了验证. 相比其他仿真方法, 模式分析极大地减少了对LED建模优化的计算复杂度, 同时从理论上阐明了不同结构参数变化引起LED光提取效率改变的原因. 研究发现, 当顶层光子晶体满足d ≈ λ / n_PhCs 时, 结构内大部分高阶导模尚未被截断但源区能量向低阶导模的转化被有效抑制, 光提取效率给出极大值. 嵌入式光子晶体的引入将激发覆盖层模式, 当满足100 nm≤ T ≤ 300 nm且100 nm≤ D ≤ 200 nm 时, 覆盖层模式可以从有源层获得较大能量并有效地与顶层光子晶体耦合, 极大地提升了光提取效率. 本文优化结果使得LED光提取效率提升了4倍, 对高性能GaN蓝光LED的设计制造具有重要意义.     

TM–TE hybridization and tunable refraction in magnetophotonic crystals

In the present work we study the photonic band structure (PBS) and the polarization state of the Bloch eigenmodes of a two-dimensional magnetophotonic crystal (MPC) with square lattice formed from magneto-optically (MO) active cylinders. The refraction of light at the boundary of the MPC is analyzed. We found that both—the PBS and eigenmodes of the MPC—are most significantly altered by the MO activity in the vicinity of the degeneracies. For this case we demonstrated the possibility of an abrupt change in the propagation direction of light by the application of a magnetic field. For the Bloch wave vectors and frequencies corresponding to non-degenerate branches, the alteration of the PBS is shown to be negligible and eigenmodes almost completely coincide with linearly TE- and/or TM-polarized eigenmodes of the non-magnetic photonic crystal.     

二维磁性光子晶体及其模场分析

利用频域有限差分方法分析了两种二维磁性光子晶体结构(方形和圆形空气孔结构)的模场分布和有效折射率. 结果表明：在该种结构的材料中，原本简并的基模被分为两个不简并的偏振模——左旋模和右旋模，且两种模式的有效折射率不同； 其次，该种结构材料的法拉第旋转角较连续分布的磁光介质有显著增加. 通过选择适当的空气孔参数，方孔结构材料的法拉第旋转角可增大约一个数量级，而圆孔结构可增加4倍左右. 同时发现，当光通过这类材料后偏振态发生了变化，随着法拉第旋转角的增加出射光的椭圆率也在增加. 最后分析了产生这一现象的原因并提出了解决偏振态变化这一问题的方法，即在材料中心处引入缺陷. 关键词： 磁光效应 二维磁性光子晶体 频域有限差分法     

One-dimensional opal photonic crystals

One-dimensional opals are 1D self-assembled close packed colloidal crystals consisting of monodisperse colloidal globules. Polystyrene globules with sizes in the 1.9–10 μm range sit on a flat substrate and touch two neighbors in diametrally opposite contact points. These opals are quasi-1D photonic crystals. Optical modes, including whispering gallery modes of individual globules, coupled collective modes, and nanojet-induced modes, are visualized in 1D opals.     

Genetic optimization of magneto-optic Kerr effect in lossy cavity-type magnetophotonic crystals

We have demonstrated an optimization approach in order to obtain desired magnetophotonic crystals (MPCs) composed of a lossy magnetic layer (TbFeCo) placed within a multilayer structure. The approach is an amalgamation between a 4×4 transfer matrix method and a genetic algorithm. Our objective is to enhance the magneto-optic Kerr effect of TbFeCo at short visible wavelength of 405 nm. Through the optimization approach, MPC structures are found meeting definite criteria on the amount of reflectivity and Kerr rotation. The resulting structures are fitted more than 99.9% to optimization criteria. Computation of the internal electric field distribution shows energy localization in the vicinity of the magnetic layer, which is responsible for increased light-matter interaction and consequent enhanced magneto-optic Kerr effect. Versatility of our approach is also exhibited by examining and optimizing several MPC structures.     

Magnetoplasmonic crystals: Resonant linear and nonlinear magnetooptical effects

Results of spectroscopic analysis of the optical second-harmonic (SH) generation in magnetic plasmonic structures comprised of iron garnet and periodic arrays of gold stripes are presented. It is shown experimentally that, in the region of the resonant excitation of a surface plasmon on the metal–magnetic dielectric interface, an increase in the SH intensity and an alternating modulation of the magnetic contrast for the SH, reaching 40%, are observed. The results are described in terms of a nonlinear Fano resonance.     

Depolarization of light in magnetooptical crystals under magnetomechanical resonance conditions

Taking into account multiple reflections inside a magnetooptical crystal under conditions of magnetomechanical resonance, we determine the change of polarization degree of light passing through the sample using methods of Muller matrices and of the Stokes vector.     

Moving double layers

Using a triple-plasma device, moving double layers have been produced by abruptly increasing the plasma density in the region of the double layers. Propagation velocities up to 3.5 c_s have been achieved with their velocity scaling as $\text{ν ～ (2e ×}\text{δ?}\text{T}{}_{\mathrm{<mtext>e</mtext>}}\text{)}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{c}{}_{\mathrm{<mtext>S</mtext>}}$.     

Nanostructured one-and three-dimensional magnetophotonic crystals based on porous silicon and artificial opals

Nanostructured one-and three-dimensional magnetophotonic crystals are produced by infiltration of yttrium-iron garnet with bismuth into photonic crystals based on porous silicon and artificial opals. The magnetic properties of the resulting structures are studied by generation of the magnetically induced second harmonics. The magnetic contrast of the second harmonics intensity in the spectral region of the photonic gap edge of the photonic crystal is 10–15%.     

复合周期的介质-液晶光子晶体研究

本文研究了掺入各向同性周期性介质层缺陷的一维复合周期胆甾型液晶光子晶体的禁带特性.发现同一般的胆甾型液晶不同,复合介质-液晶周期结构对左旋偏振入射光和右旋入射光都会出现共同禁带.当各向同性介质层占一个周期的厚度比例越小,左旋偏振光的禁带效应逐渐消失,而右旋偏振光的禁带则逐渐合并变大;且各向同性介质的折射率越大,则两种偏振光的禁带效应越明显,更容易出现共同禁带;通过调整厚度比,可以在可见光范围内出现对应红、绿、蓝色波长的禁带,从而可以用于液晶显示的反射式彩色滤光片. 关键词： 胆甾型液晶 光子晶体 禁带 缺陷     

Laboratory double layers with no external fields

It is shown that the formation of double layers in a triple plasma device does not require an externally applied electric field across the plasma boundaries.     

Propagation of circularly polarized waves in one-dimensional bragg structures (magnetophotonic crystals)

A theory of electromagnetic wave propagation in structures formed by alternating magnetic and dielectric layers is proposed. Models of macroscopically thick and atomically thin layers magnetized perpendicular to their plane are considered. Transfer matrices of circularly polarized waves and characteristics of light propagation in periodic magnetic structures under normal incidence are obtained by the self-consistent electrodynamic Green’s function method in analytic form. The results obtained are employed to analyze linear-in-magnetization magneto-optical effects in the transmittance and reflectance spectra of one-dimensional magnetic Bragg structures called magnetophotonic crystals. For structures of finite thickness, Faraday rotation and other observable magneto-optical quantities are shown to vary appreciably in the spectral region of the stop bands of a magnetophotonic crystal. This is paralleled by a substantial enhancement of the magnetic-fieldinduced modulation of the reflectance of light polarized in the analyzer plane.