光子晶体制备技术和应用研究进展

从光子晶体概念的提出到现在已经过了20余年,光子晶体不仅成为微纳光子学和量子光学的重要研究领域,而且在信息光学以及其他多个学科中得到广泛应用.本文重点综述了光子晶体的制备工艺,尤其是二维光子晶体和三维光子晶体的制备工艺进展,同时也综述了光子晶体的应用研究的进展,在此基础上,提出了一些光子晶体研究的展望.     

光子晶体的制备方法及其应用

光子晶体是一种介电常数不同的、其空间呈周期分布的新型光学材料。由于光子晶体具有光子带隙、光子局域和控制光子态密度等特性,所以它具有广阔的应用前景。简述了光子晶体的主要特征,重点介绍了其制备方法、进展以及实际的和潜在的应用。     

一维函数光子晶体的研究

本文提出一种新型函数光子晶体, 其折射率是空间位置函数. 由费马原理, 我们给出光在一维、 二维和三维函数光子晶体中的运动方程, 以及一维函数光子晶体的色散关系、 带隙结构和透射率, 再利用传输矩阵理论研究函数光子晶体周期数、 入射角和介质层的厚度等对透射率和禁带结构的影响, 计算发现通过选择不同的折射率空间分布函数, 可以得到比传统光子晶体更宽或更窄的禁带结构. 这样为我们设计不同带隙结构的光子晶体提供理论依据.     

二维函数光子晶体

光子晶体是由两种或两种以上不同介电常数材料所构成的周期性光学纳米结构.光子晶体结构可分为一维、二维和三维,其中二维光子晶体已成为研究的热点.可调带隙的二维光子晶体可以设计出新型的光学器件,因此,对它的研究具有重要的理论意义和应用价值.本文提出的二维新型函数光子晶体可以实现光子晶体带隙的可调性.所谓二维函数光子晶体,即组成它的介质柱的介电常数是空间坐标的函数,它不同于介电常数为常数的二维常规光子晶体.二维函数光子晶体是通过光折变非线性光学效应或电光效应使介质柱的介电常数成为空间坐标的函数.运用平面波展开法给出了TE和TM波的本征方程,由傅里叶变换得到二维函数光子晶体介电常数ε(r)的傅里叶变换ε(G),其傅里叶变换比常规二维光子晶体的复杂.计算发现当介质柱介电常数为常数时,其傅里叶变换与常规二维光子晶体的相同,因此二维常规光子晶体是二维函数光子晶体的特例.在此基础上具体研究了二维函数光子晶体TE波和TM波的带隙结构,其介质柱介电常数函数形式取为ε(r)=k·r+b,其中k,b为可调的参数.并与二维常规光子晶体TE波和TM波的带隙结构进行了比较,发现二维函数光子晶体与二维常规光子晶体TE波和TM波的带隙结构有明显的区别,二维函数光子晶体的带隙数目、位置以及宽度随参数k的变化而发生改变.从而实现了二维函数光子晶体带隙结构的可调性,为基于二维光子晶体的光学器件的设计提供了新的设计方法和重要的理论依据.     

一种发光二极管模型中无序光子晶体对光输出影响的研究

摘要利用Order-N算法及超晶格技术讨论了位置无序及尺寸无序对石墨点阵柱状光子晶体光子带隙的影响.计算结果表明，对于电场偏振模，光子带隙对尺寸无序更加敏感.在此基础上，利用三维时域有限差分方法进一步讨论了无序光子晶体对石墨点阵柱状中心柱光子晶体GaN发光二极管模型光输出效率的影响.计算结果表明，无序对这种光子晶体发光二极管模型光输出效率的影响较小，且这种影响也是随机的.     

三维光子晶体FCC结构的带隙分析

采用平面波展开法研究了由介质球构成的蛋白石的三维光子晶体FCC结构的能带结构,改变r/a的大小获取最大完全带隙,并计算了在双球结构中改变一个小球的变化所引起的三维光子晶体带隙的变化。结果为三维光子晶体的实验和应用提供了一些指导和帮助。     

非水溶性光致聚合物光子晶体的研制

报道了一种新型的利用激光全息技术制作光子晶体的记录材料,即自制的非水溶性光致聚合物.用绿光作为光源对材料性能参量做简单测试,经测试其衍射效率可达85%,在波长为514.5 nm处拥有较高的吸收率,且该材料的后处理过程简单,只需热烘.利用Matlab简单模拟全息法制作光子晶体的过程,经模拟得到干涉的光束越多,光子晶体的晶格结构越复杂.设计了制作二维、三维光子晶体的实验光路,分光元件分别为掩模板和去顶棱镜.实验结果表明,利用非水溶性光致聚合物可制作大面积、大体积、耐高温和高强度的二、三维光子晶体,且其晶体结构与Matlab模拟的结果基本一致|利用非水溶性光致聚合物作为记录材料时,光路的搭建是影响实验结果的重要因素.     

木堆结构三维光子晶体带隙特性

基于平面波展开法研究木堆结构三维光子晶体带隙特性.用硅材料构成木堆结构三维光子晶体,改变结构中木条的宽度和长度,得到当木堆条宽度为5μm,高度为7μm时形成的带隙结构较宽,在0.2899-0.3804Hz,带隙宽度为0.0905Hz.改变构成木堆结构三维光子晶体的材料,得到锗材料构成木堆结构三维光子晶体带隙结构在0.2585-0.3500Hz,带隙宽度为0.0915Hz,带隙相比硅材料和碳化硅材料较宽.研究结论为三维光子晶体的制备提供参考.     

三维光子晶体压力传感器的研究

基于平面波展开法,分析聚苯乙烯三维光子晶体的能带结构和传输特性.研究聚苯乙烯三维光子晶体对压力的响应性质;计算结果表明:0~41.3 MPa的外加压力与归一化频率0.596~0.608之间具有良好的线性关系,通过测量归一化频率可以感知压力的大小;由于光子晶体的结构周期与光波长为一个数量级,也就有可能制造出一系列精巧的三维光子晶体压力传感器.     

Ta_2O_5/MgF_2异质结构三维光子晶体的偏振性

为了在可见及近红外波段得到具有良好带隙结构的三维光子晶体,利用传输矩阵法分析了MgF2、Ta2O5以及Ta2O5/MgF2异质结构三维光子晶体的带隙性质.结果表明:Ta2O5/MgF2异质结构三维光子晶体在820～1020nm的近红外波段TM模式下具有不受入射光方向影响的全方位光子带隙.该结构有望用于制作近红外光波段的偏振器件.     

Infiltrated Liquid Crystal Photonic Bandgap Devices for Switching and Tunable Filtering

In this article the possibility of obtaining a tunable bandgap by using infiltrated liquid crystal photonic bandgap structures is explored. In particular, by exploiting the electrooptic effect and the electroclinic effect, peculiar to two different kinds of liquid crystals, the switching and tunable filtering operation of a three-dimensional photonic crystal has been analyzed by means of a differential method combined with an S-matrix algorithm.     

Infiltrated Liquid Crystal Photonic Bandgap Devices for Switching and Tunable Filtering

In this article the possibility of obtaining a tunable bandgap by using infiltrated liquid crystal photonic bandgap structures is explored. In particular, by exploiting the electrooptic effect and the electroclinic effect, peculiar to two different kinds of liquid crystals, the switching and tunable filtering operation of a three-dimensional photonic crystal has been analyzed by means of a differential method combined with an S-matrix algorithm.     

Si-based two-dimensional photonic crystals coupled to one-dimensional Bragg mirrors

Planar two-dimensional photonic crystals can be combined with a one-dimensional Bragg mirror to control the quality factor and out-of-plane coupling of optical Bloch modes. We have investigated the optical properties of such structures fabricated on silicon. The photonic crystals are fabricated in the upper Si layer deposited on top of quarter-wave thick SiO₂-polycrystalline Si layers. The optical properties are probed by the room-temperature photoluminescence of Ge/Si self-assembled islands as an internal source. We show that an enhancement of the quality factor can be obtained by controlling the thickness of the silicon upper layer in which the two-dimensional photonic crystal is etched and by controlling the air filling factor of the photonic crystal. Quality factors of 2200 around 1100 nm are obtained by this method for defect-free photonic crystals with a square lattice pattern. The experimental results are supported by three-dimensional finite-difference time-domain (FDTD) calculations of the radiated modes for the investigated structures.     

Fabrication and characterization of three-dimensional metallodielectric photonic crystals for infrared spectral region

We propose a technique for the realization of three-dimensional metallodielectric photonic crystals based on fabricating polymeric structures using the interference lithography followed by the magnetron deposition of a gold nanolayer. The infrared reflectance spectra of the fabricated photonic crystals are studied. The spectrometry and finite-difference time-domain modeling data show that there is a photonic band gap centered at the wavelength approximately equal to the photonic crystal period.     

A colloidal crystal microstructure fiber: fabrication and characterization

A method of fabricating colloidal crystal microstructured fiber is presented. The proposed structure relies on partial etching of the cladding layer of a single-mode fiber and growth of colloidal photonic crystals inside eroded area. The photonic crystal cylindrical annulus embedded in fiber is characterized by optical and scanning electron microscopy. The optical characterization was analyzed by optical transmission spectroscopy. The measurement results show a about 1550-nm band gap. The results also reveal the possibility of cladding cylindrical fibers with three-dimensional photonic crystals.     

Optical Anisotropy of Photonic Crystals of Cubic Symmetry Induced by Multiple Diffraction of Light

The optical spectra of Bragg reflection from opal-like photonic crystals under conditions of the resonant enhancement of the multiple diffraction of light have been studied experimentally and theoretically using the photonic crystal structures prepared of monodisperse polystyrene globules. It is shown that the reflection signal registered in mutually orthogonal configurations of the polarizer and analyzer is related to the intrinsic optical anisotropy of the crystals and is a specific manifestation of the multiple Bragg diffraction in three-dimensional photonic crystals.     

A simple method for fabricating two- and three-dimensional photorefractive photonic lattices microstructures

We demonstrate an approach for easy fabrication of two- and three-dimensional optically induced nonlinear photonic lattices microstructures in photorefractive crystal by applying spatial filter and amplitude mask. The experimental setup of this method is very simple and flexible without complicated optical adjustment system. It can be applied in almost any optical laboratories. Two-dimensional hexagonal, square and three-dimensional hexagonal nonlinear photonic lattices microstructures have been produced in an iron-doped lithium niobate photorefractive crystal. The period of the induced photonic lattices microstructures can be dominated easily. This method is easily extended to generate more complex photonic lattices microstructures in photorefractive crystals, such as quasicrystal lattice.     

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%.