【作者】 刘占芳；

【导师】 张国； 宋恺；

【作者基本信息】 吉林大学 ， 高分子材料工程， 2008， 博士

【摘要】 具有掺杂等复合结构,是三维光子晶体从简单材料走向复杂器件的重要一步。通过具有掺杂态的光子带隙来改变荧光发射,得到特定波长的荧光光谱窄化,对在微/纳米尺度体系内获得激光发射或类激光发射具有重要理论意义。空心微球组成的光子晶体,通过液体渗入来调节光子晶体的带隙波长和强度,可通过光子带隙波长和强度的改变来表征液体折光率变化。本文利用多层光子晶体的复合光子带隙,得到荧光光谱的窄化效应,并可以有效地对荧光发射光谱进行修饰。在有效改进光子带隙对荧光发射的整体抑制作用后,期望能够在此体系内获得类激光发射。通过将相同尺寸、不同折光率的微球组装在一起,单一地获得介电常数掺杂的三维光子晶体,从而清晰肯定地确认掺杂状态为给体掺杂还是受体掺杂,并通过对应光子带隙中缺陷态的位置,为进一步理论分析缺陷态和掺杂状态的关系奠定基础。利用二氧化硅致密空心球来有效降低光子晶体的有效折光率,在通过液体渗入调节光子带隙的过程中,有效实现光学结构从蛋白石向反蛋白石结构的反转,从而在调节光子带隙波长位置的同时,大幅提高了光子带隙的强度,更加有利于光子晶体带隙的调控。更多还原

【Abstract】 Photonic crystals,namely photonic bandgap materials,are artificially arranged periodic electromagnetic structure in optical wavelength scale. Due to the periodic modulation of the refraction index, they possess photonic band gaps that inhibit the existence of light in certain frequency ranges, which is analogous to what the semiconductor do to the electrons. In the last decade, photonic crystals have been a rapidly developing field because of their novel optical properties and important potential applications. It also does not present the complete photonic bandgap(PBG) owing to the low rwfractive index(RI) and low RI contrast of the components. To realize the complete PBD and to rich the propertiea of PCs, an effective route is to mix of different materials into the three-dimensional (3D) ordered structures. There are two main ways to make the composites: by synethesizing composite spheres prior to buliding the PCs(so-called as bottom-up route) or by synthesing new materials in or around the pores of an assemble opal (so-called as top-down route).This dissertation focouses on multilayer photonic crystal for spectral narrowing of emission, inverse opal-like crystal of liquids and refractive index doping of photonic crystals.A quaternary system, consisting of air, an air-core/dense-silica-shell core-shell particle, and liquids has been used to fabricate an inverted opal structure with low fill factor, high refractive index contrast and reversible tuning capabilities of the bandgap spectral position. The original close-packed opal structure is a ternary self-assembled photonic crystal from monodisperse and spherical polystyrene-core/silica-shell colloidal particles with air as the void material. Calcination removed the polystyrene and converted the core-shell particles to hollow spheres with a dense shell. In a final step, liquid is infiltrated only in the voids between the hollow spheres, but does not penetrate in the shell. This allows facile and reversible tuning of the bandgap properties in an inverted opal structure.Multilayer colloidal crystal has been prepared by the layer-by-layer deposition of silica microspheres on a glass slide. Each layer is a slab consisting of a fcc close-packed colloidal arrays. By properly choosing the sizes of spheres, the whole spectral feature of multilayer colloidal crystal can be tuned. Here, we engineered a multilayer superlattice structure with an effective passband between two stop bands.This gives a strong narrowing effect on emission spectrum. With the stop bands at the shortwave and longwave edges of emission spectrum, the passband in the central wavelength region can be regarded as a strong decrease of suppression effect and enhancement of a narrow wavelength region of emission. The spectral narrowing modification effect of suitably engineered colloidal crystals shows up their importance in potential application as optical filters and lasing devices.One of the structures that can be fabricated using heterostructure is obtained by inserting a low-band-gap semiconductor between two higher-gap materials.In face, it has destroied face-centered cubic(FCC) structure of photonic crystals,and can not prove the theory about the defect.We choose silica hollow spheres as defect inserting colloid crystals, which have different dielectric constant with silica spheres. By successively depositing a multilayer crystal using convective self- assembly and then deposition a single layer using Langmuir-Blodgett(LB) technique and, finally, again depositing a multilayer ,we succeeded in introducing a microcavity into a self-assembled crystal. There are obviously stopband in spectrum.更多还原