New Configuration of Ring Resonator in Photonic Crystal Based on Self-Collimation

We propose a novel ring resonator configuration in a channelless photonic crystal. The proposed ring resonator utilizes the self-collimation effect and the bending and splitting mechanisms of line defects to route the propagation of light, instead of conventional indexed-guided waveguides or photonic crystal band gap waveguides. The finite-difference time-domain method (FDTD) is used to investigate the characteristics of the ring resonator. The new design exhibits an ON--OFF contrast with an extinction ratio of more than 12dB, and has an ultra-compact footprint of 3.3×3.3μm² when it operates at the optical communication wavelength λ=1.55μm. The design presented may find applications in the areas including ultra-compact optical switch and wavelength filer in integrated optical circuits.     

Highly-Ordered Ferroelectric Photonic Crystals

Highly-ordered, ferroelectric, Pb-doped Ba0.7Sr0.3TiO3, inverse opal thin films were fabricated using a sol-gel spin coating technique. The excellent crystal quality is evident from the SEM images and the good agreement between the theory and experiments.     

Optics of Photonic Crystals

In this article, a general theoretical framework to describe and analyze the optical properties of photonic crystals is presented. In addition to the analytical treatment of their optical response based on the method of Green’s function, numerical tools to calculate the dispersion relations and the eigenfunctions of the radiation field, transmission spectra, localized midgap modes, and lasing threshold are introduced and applied to some typical examples. Group theory to analyze the symmetry of the eigenmodes is also introduced, and the existence of uncoupled modes that cannot be excited by external plane waves is shown. The presence of the enhancement effect of nonlinear optical processes and stimulated emission due to the small group velocity which is easily realized in the photonic crystals is pointed out, and the possibility of low-threshold lasing in the photonic crystals is discussed.     

利用冲击波作用光子晶体产生蓝光的研究

研究了一种利用冲击波作用光子晶体产生蓝光的新方法.通过模拟光子晶体受冲击波作用后折射率的变化,对470nm蓝光,设定光子晶体的参量,研究了冲击波引起光子晶体带隙的变化,计算了需要冲击波的速度,分析了影响蓝光线宽和中心波长的因素.结果表明,变频后的光波线宽随冲击波和固定反射面的距离而变化,距离大时,线宽较小,距离小时,线宽较大,可以利用光子晶体的滤波作用对输出光波线宽进行控制,获得带宽稳定的或变化的输出光波.环境温度变化、光子晶体材料吸收特性影响光子晶体的带隙分布,进而影响蓝光的中心波长.研究结果对研制新的蓝光光源具有重要参考价值,同时也为其他相干光源的产生提供了一种新的技术.     

利用冲击波作用光子晶体产生蓝光的研究

研究了一种利用冲击波作用光子晶体产生蓝光的新方法.通过模拟光子晶体受冲击波作用后折射率的变化,对470 nm蓝光,设定光子晶体的参量,研究了冲击波引起光子晶体带隙的变化,计算了需要冲击波的速度,分析了影响蓝光线宽和中心波长的因素.结果表明,变频后的光波线宽随冲击波和固定反射面的距离而变化,距离大时,线宽较小,距离小时,线宽较大,可以利用光子晶体的滤波作用对输出光波线宽进行控制,获得带宽稳定的或变化的输出光波.环境温度变化、光子晶体材料吸收特性影响光子晶体的带隙分布,进而影响蓝光的中心波长.研究结果对研制新的蓝光光源具有重要参考价值,同时也为其他相干光源的产生提供了一种新的技术.     

Raman Scattering in Three-Dimensional Photonic Crystals

The optical properties of three-dimensional photonic crystals associated with the form of reflection spectra from their surface (appearance of a forbidden gap in the energy spectrum) and with the specific features of Raman scattering are analyzed. Idealized models of the energy band structure of photonic crystals are studied. Expressions for the group velocity of photons with energy close to the forbidden gap are derived. Experimental results on the Raman scattering in photonic crystals based on artificial opal as well as in fused silica are discussed. Bands due to quantum-size effects (presence of nanoclusters in fused silica and nanoglobules forming the lattice of globular photonic crystals) were manifested in the spectra of inelastic light scattering. It is proposed to use photonic crystals for the creation of sensitive sensors of organic and inorganic substances using modern Raman techniques.     

Left-Handed Properties in Two-Dimensional Photonic Crystals Formed by Holographic Lithography

We give an analysis of the frequency distribution trends in the four lowest bands of two-dimensional square lattices formed by holographic lithography （HL） and in the lattices of the same kind but with regular dielectric columns with increasing filling ratios, and then present a comparative study on the left-handed properties in these two kinds of structures using plane wave expansion method and finite-difference time-domain （FDTD） simulations. The results show that the left-handed properties are more likely to exist in structures with large high-epsilon filling ratios or in a connected lattice.     

Compton散射对非均匀等离子体光子晶体光子带隙的影响

应用多光子非线性Compton散射模型和时域有限差分法,对多光子非线性Compton散射对非均匀等离子体光子晶体光子带隙特性的影响进行了研究,提出将入射和散射光作为形成光子带隙的新机制,对电磁波方程进行了修正.结果表明:与Compton散射前相比,散射使电磁波幅值衰减更快|随等离子体密度增加,透射谱禁带宽度几乎无变化,其中心频率向高频方向有明显移动,向上的峰值有较大增加,反射谱向下的峰值有明显减小|随温度增加,透射谱禁带宽明显减小,向上的峰值略有减小,透射能量有所降低|随两种介质介电系数比增加,光子禁带数增加,且带隙间距显著减小.     

基于冲击波作用于光子晶体实现光学频率变换方法的分析

分析了光子晶体实现光学频率变化的方法。阐述了光子晶体光学频率变换的原理,用软件仿真了冲击波作用光子晶体的折射率变化和带隙变化,分析了冲击波速度和冲击波作用光子晶体时间的长短对光学频率变化的影响,结论表明,冲击波速度越大光学频率的变化量越大,冲击波作用光子晶体的时间越长光学频率的变化量越大。由于利用光子晶体的禁带特性,能够对落入光子晶体禁带中的光波实现全反射,故频率转换效率很高。此种方法在近几年发展起来的可调谐激光器有重要的应用,也是光子晶体一个新的研究领域。     

两端有慢变结构的光子晶体的能带特性研究

研究了几种两端有慢变周期结构的光子晶体的能带特性,研究发现,通过在普能光子晶体两端添加适当的慢变周期结构,可以使光子晶体的光子禁带区向短波区或向长波区扩展,也可以同时向短波和长波两个区域扩展,与普通结构的光子晶体的光子禁带宽度相比,可以获得400％以上的禁带区宽度的拓展。     

Hybrid Parametric Solitons in Nonlinear Photonic Crystals

We analyze the characteristics of a three-frequency spatial parametric soliton formed by virtue of the cascade frequency tripling in quadratic, periodically poled crystals. A variational approach and a method of averaging are developed, which make it possible to describe analytically, with good accuracy, the characteristics of the spatial solitons studied numerically.     

Spatially Inhomogeneous Gain Modification in Photonic Crystals

The electric and magnetic energy distributions in photonic crystals （PC） are calculated by using the plane wave expansion （PWE） method. Even though the total electric and magnetic energy in each unit cell of photonic crystals are equal to each other, the ratio of electric and magnetic energy densities varies depending on the local position. Based on Fermi＇s golden rule, the optical gain is analysed in the full quantum framework that takes the nonuniform energy density ratio into account. This nonuniform energy density ratio in photonic crystals, defined in an equal form as gain modification factor, leads to spatially inhomogeneous modification of optical gain. Results reported in the paper provide a new perspective for analysing gain characteristics, as well as the lasing properties, in photonic crystals.     

一维类梳状光子晶体中的缺陷模研究

本文研究了一种一维类梳状光子晶体的事结构及缺陷态对带隙的影响。发现这种结构的带隙来源于结构 周期性及所接分支所形成的共振态。通过移去或插入一定数目的缺陷分支在带隙中将形成局域态,通过对透射系数的研究,发现局域态以窄的尖峰形式出现在透射谱中,并且,局域态的性质与所接缺陷的数目、缺陷分支的长度及所接的位置有关。     

Three-Dimensional Photon Control in Membrane-Stack Photonic Crystals

We design two novel waveguides in membrane-stack photonic crystals and obtain their dispersion characteristics by the three-dimensional （3D） plane wave-expansion method. The 3D photon control phenomena are demonstrated, in which light is incident on the crystal and is bent both horizontally and vertically. Then light is split into two and is finally emitted from the other side of the crystal. A 319 splitter is realized. We also present a nanocavity to trap photons. With waveguides of different directions has been demonstrated. and nanocavities, the arbitrary 3D photon manipulation     

Photonic Band Gap Properties of Three-Dimensional SiO2 Photonic Crystals

Three-dimensional SiO2 photonic crystals （PhCs） are fabricated on quartz substrates by the vertical deposition method. Scanning electron microscopy measurement reveals that the samples exhibit an ordered close-packed arrangement of SiO2 spheres. It is found that the position of the [111] photonie band gap （PBG） shifts to a long wavelength （red shift） with increasing sphere size. Gap broadening effects are observed due to the presence of defects in the samples. Moreover, the optical properties of the PBG are very sensitive to the annealing temperature. Our results indicate that the optical properties of the PBG can be easily tuned in the visible region by appropriate experimental parameters, which will be useful for practical applications of PhC optical devices.     

Waveguiding in All-Garnet Heteroepitaxial Magneto-Optical Photonic Crystals

JETP Letters - We report the properties of 1D all-garnet heteroepitaxial 21 layered magneto-optical photonic crystal designed and fabricated for the resonance wavelength 750 ± 3 nm. It is...     

Effective Light Dynamics in Perturbed Photonic Crystals

In this work, we rigorously derive effective dynamics for light from within a limited frequency range propagating in a photonic crystal that is modulated on the macroscopic level; the perturbation parameter \({\lambda \ll 1}\) quantifies the separation of spatial scales.We do that by rewriting the dynamical Maxwell equations as a Schrödinger-type equation and adapting space-adiabatic perturbation theory. Just like in the case of the Bloch electron, we obtain a simpler, effective Maxwell operator for states from within a relevant almost invariant subspace. A correct physical interpretation for the effective dynamics requires establishing two additional facts about the almost invariant subspace: (1) The source-free condition has to be verified and (2) it has to support real states. The second point also forces one to consider a multiband problem even in the simplest possible setting; This turns out to be a major difficulty for the extension of semiclassical methods to the domain of photonic crystals.     

缺陷态光子晶体带隙特性的计算机仿真

基于平面波展开法,设计缺陷态二维正方晶格光子晶体结构,改变构成缺陷态结构的材料、占空比,应用Matlab语言计算机仿真得到,高介电常数材料构成的缺陷态光子晶体形成较宽的横磁波光子带隙,占空比在30％时形成较宽的横磁波光子带隙.研究结论为缺陷态光子晶体滤波器件的制作提供理论依据.     

一维无序结构光子晶体的能带特性研究

通过引入结构参数a,深入研究了具有无序结构的一维二元光子晶体的能带特性。研究发现,无序结构有效拓宽了光子带隙,与均匀结构相比,拓宽率达到200％以上;无序一维光子晶体表现出从可见到红外很宽区域的高反射特性。本文还计算和分析了入射角和无序度D对光子晶体带隙的影响。