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.     

全息制作不同晶面取向光子晶体模板

用单向光入射和单次曝光的激光全息技术制作了类金刚石结构, 此类金刚石结构有宽完全带隙和低介质折射率要求等优点. 在同一种光束配置下，引入恰当的匹配棱镜，用激光全息技术制作了大面积的类金刚石光学晶格不同晶面取向的亚微米周期结构. 满足如负折射效应等研究中所需的特殊晶面取向要求. 关键词： 激光全息技术 光学晶格 光子晶体     

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。     

半导体量子阱材料微加工光子晶体的光学特性

利用聚焦离子束刻蚀方法和电子束制版结合干法刻蚀方法制备了二维近红外波段光子晶体，发现两种方法都可以制备出均匀的二维光子晶体，聚焦离子束方法操作简单，电子束制版结合干法刻蚀方法操作步骤复杂.光谱测试表明，利用聚焦离子束方法在有源材料上刻蚀的光子晶体不发光，而电子束制版结合干法刻蚀方法制备的小晶格常数光子晶体即使有些无序，其出光效率也提高到没有光子晶体时的两倍.对两种方法所加工的光子晶体不发光和提高出光效率的机理进行了分析. 关键词： 聚焦离子束 电子束制版 光子晶体 出光效率     

基于不同液晶填充光子晶体光纤传输特性的研究

将5种不同折射率的液晶分别填入实芯光子晶体光纤的空气孔中, 通过改变外场条件, 研究其输出光谱的变化规律, 并进行了理论模拟分析. 结果表明: 填充液晶后, 输出光谱由全通变为多个波峰的带隙式; 同时, 液晶的折射率差值越大, 其波峰位置越向长波长方向移动, 且相对光强的对比度可以达到16 dB; 温度由20 ℃上升到85 ℃时, 波峰向短波长方向移动, 最大调控范围可达41 nm; 调节电压从0-250 V, 输出光谱的相对光强变小, 但波峰具有较好的稳定性; 在室温下, 波峰不随入射光偏振态的变化而变化. 该液晶光子晶体光纤可应用于温控可调谐滤波器或电控衰减器.     

A photonic crystal waveguide with silicon on insulator in the near-infrared band

A two-dimensional (2D) photonic crystal waveguide in the \Gamma--K direction with triangular lattice on a silicon-on-insulator (SOI) substrate in the near-infrared band is fabricated by the combination of electron beam lithography and inductively coupled plasma etching. Its transmission characteristics are analysed from the stimulated band diagram by the effective index and the 2D plane wave expansion (PWE) methods. In the experiment, the transmission band edge in a longer wavelength of the photonic crystal waveguide is about 1590\,nm, which is in good qualitative agreement with the simulated value. However, there is a disagreement between the experimental and the simulated results when the wavelength ranges from 1607 to 1630\,nm, which can be considered as due to the unpolarized source used in the transmission measurement.     

二维圆柱形光子晶体的完全禁带研究

用平面波展开法研究了二维圆柱形光子晶体的完全禁带与填充比、介电常数比之间的关系. 研究发现,并非介电常数比越大,完全禁带宽度就越大,而是有一个峰值. 关键词： 二维光子晶体 完全禁带 平面波展开法     

Parameters for efficient growth of second harmonic field in nonlinear photonic crystals

The ultrashort pulse propagation and nonlinear second harmonic generation under the undepleted pump approximation in a quadratic nonlinear photonic crystal (NPC) structure is theoretically investigated and the optimized parameters for high second harmonic generation conversion efficiency are extracted. The transfer matrix method is used for the numerical formulation for oblique angle of incidence. A unique set of material combination GaInP/InAlP is selected as alternating nonlinear and linear layers. The NPC parameters like incident angle and layer thickness are manipulated to obtain the exact phase matching using double resonance condition for a fixed number of layers with known experimental material parameters.     

Applied electric field to fabricate colloidal crystals with the photonic band-gap in communication waveband

The macropore silica colloidal crystal templates were assembled orderly in a capillary glass tube by an applied electric field method to control silica deposition. In order to achieve the photonic band gap (PBG) of colloidal crystal in optical communication waveband, the diameter of silica microspheres is selected by Bragg diffraction formula. An experiment was designed to test the bandgap of the silica crystal templates. This paper discusses the formation process and the close-packed fashion of the silica colloidal crystal templates was discussed. The surface morphology of the templates was also analyzed. The results showed that the close-packed fashion of silica array templates was face-centered cubic (FCC) structure. The agreement is very good between the experimental data and the theoretical calculation.     

光子晶体的光学特性与近场光学测量表征

光子晶体具有独特而优异的光学特性及广泛的应用前景。介绍了光子晶体的概念、应用、发展,着重讨论了光子晶体的光子禁带、光子局域以及其它光学特性。从近场光学的原理和实验技术出发阐述了近场光学测量表征光子晶体的方法,对于光子晶体的研究具有重要的意义。     

3D photonic crystals based on macroporous silicon: Towards a large complete photonic bandgap

Recently, a new three-dimensional photonic crystal consisting of two interpenetrating hexagonal pore sets was introduced. Here, we investigate the influence of possible experimental errors including shift, tilt and rotation of one pore set on the size of the bandgap theoretically and determine fabrication tolerances. A structure is fabricated in silicon using photo-electrochemical etching and subsequent focused ion beam milling. The change of the cross-section of the milled pores with pore depth is investigated and reflection measurements along different directions are performed indicating the low frequency edge of the photonic bandgap.     

Optical characteristics of one-dimensional photonic crystals composed of high-aspect-ratio Si walls fabricated on V-grooved wafer

We demonstrate optical properties of one-dimensional photonic crystals (PC), which are fabricated using high-aspect-ratio etching on a V-grooved silicon wafer. The measured transmission spectrum has an obvious band gap; the suppression is over 30 dB. The quite small insertion loss of 1.9 dB is achieved by induced coupled plasma (ICP) cryogenic etching and direct coupling to the optical fiber aligned in the V-groove. We also successfully observed peaks originating from a localized cavity mode. Such a microcavity enables control of the light, which qualifies photonic crystal as a fundamental structure of optical functional devices. These results lead to achievement of integrated Si-based photonic circuits.     

非密堆积TiO2空心微球光子晶体的制备与能带分析

利用胶体自组装、高温烧结和HF酸刻蚀技术,制备了SiO₂微球非密堆积面心立方(FCC)结构的胶体晶体,并以此为模板,利用溶胶凝胶方法和NaOH湿法刻蚀技术制备了TiO₂空心微球非密堆积FCC结构光子晶体.利用电子显微镜分析了晶体的结构,用平面波展开法对该结构进行了能带计算与分析.计算结果表明,制备的TiO₂空心微球非密堆积FCC结构光子晶体在低能区的第二、第三能带之间除布里渊区的W点仍保持简并外,其余各点简并都已经消除. 关键词： 空心微球 非密堆积 光子晶体 光子带隙     

Graphite格子光子晶体带隙的数值模拟

采用平面波展开法模拟计算了由锗圆柱构成的Graphite格子二维光子晶体的带隙结构,发现由空气背景中的介质柱构成的二维Graphite格子结构的光子晶体具有完全光子带隙,并得到了使完全带隙最大化的结构参数。数值计算结果表明,Graphite结构二维光子晶体在填充比从f=0.058到f=0.605连续变化的很大范围内都有完全带隙出现,在低能区出现了Δ=0.053(ωa/2πc)的较大带隙。     

蛋白石型光子晶体红外隐身材料的制备

基于光子晶体的红外隐身材料,主要采取一维层层堆叠结构和三维木堆结构等来实现对红外波段电磁波辐射性能的调控.本文报道了一种操作简易、成本低廉的光子晶体红外隐身材料制备方法.通过优化的垂直沉积法,微米级SiO_2胶体微球自组装成高质量的蛋白石型光子晶体结构.对SiO_2胶体微球进行优选,成功制备了禁带位于2.8—3.5μm,8.0—10.0μm的SiO_2胶体晶体蛋白石型光子晶体材料.该材料可改变目标相应波段的红外辐射特征,具有目标红外波段的隐身效果.     

纳米压印技术制备表面光子晶体LED的研究

利用表面光子晶体能大幅提高发光二极管(LED)的外量子效率, 但如何制备大面积的纳米光子晶体是该研究方向的主要难点之一. 本文基于纳米压印技术在氮化镓基发光二极管(GaN-LED)表面制作孔状二维光子晶体. 通过以金属和聚合物双层掩膜干法刻蚀法, 得到了很好的光子晶体图形转移效果. 最终在LED的p-GaN层表面获得了大面积光子晶体, 周期为450 nm, 纳米孔直径为240 nm. 器件测试结果显示, 有表面光子晶体的LED比没有光子晶体的LED, 光致发光强度峰值提高到了7.2倍.     

Etching effect of the autocloning structure using ion-assisted deposition

Based on the autocloning technique the photonic crystals were fabricated using E-beam gun evaporation with ion-assisted deposition (IAD) on the periodic corrugation patterns of substrates. In this research, the surface evolution function based on the unified process model was simulated to analyze the influence of the etching and redeposition effects of the different etching time. As the etching time was longer, the top roof angle was larger and the redeposition thickness was getting thicker. The difference of the top roof angle in the experiment and the simulated result are less than 4°. It shows the simulation method achieved very good agreement with the fabricated result for different etching times from 40 to 120 min. We found the surface angular was depended on the etching effect more than the redeposition effect.     

光子晶体理论研究的新方法——混合变分法

利用混合变分法研究了二维光子晶体的能带结构,得到了通带、禁带和群速度,并详细分析光子晶体中的电磁场分布和能流密度分布.该方法方便实用,理论上能够应用于任意维度任意周期结构的光子晶体的计算.     

通讯波段禁带胶体光子晶体的制备及实验参数研究

采用直径为700nm的二氧化硅微球,通过垂直沉积法在玻璃基片上制备了位于光通讯波段的禁带胶体光子晶体。研究了不同蒸发温度、湿度条件、干燥过程对样品晶体质量的影响。用扫描电子显微镜(SEM)对其形貌进行了观测。实验结果表明,在温度为65℃,相对湿度为70%,缓慢干燥条件下制备出的样品具有较好的晶体质量,晶体在大范围内保持了面心立方(FCC)单晶结构,其(111)面平行于生长基片。     

Extremely low optical transmittance in the stopbands of photonic crystals

We demonstrate extremely low transmittance characteristics of photonic crystals (PhCs) with a finite thickness in specific photonic bandgaps (PBGs) through numerical simulation, and clarify its origin. Some of the PhCs support decaying Bloch eigenmodes, whose propagation constant (real part of the Bloch wavenumber) as well as their decay constant (imaginary part) changes with frequency inside the bandgap. Such a class of modes can interfere destructively at the exit end of the crystal depending on their round-trip phase change, which creates comb-like valleys in their transmission spectra.