【作者】 朱永胜；

【导师】 张汉壮； 宋宏伟；

【作者基本信息】 吉林大学 ， 光学， 2014， 博士

【摘要】 自从1987年光子晶体的概念被首次提出以来，已经引起了学术界广泛地关注。这种长程有序的结构使折射率在光学波长的尺度产生周期性地调制，从而导致光子带隙地形成。当所采用的材料满足布拉格散射条件时，由于光子带隙地抑制作用，特定频率的光就会禁止在光子晶体内传播。光学性质的空间周期性调制为产生和发展新的光电子器件开拓了新的空间。在光子晶体的特殊性质中，一个非常重要的方面就是对嵌入光子晶体中的发光客体自发辐射地调制作用。根据费米黄金规则，在相应自发辐射的频率范围内，自发辐射速率在弱场范畴正比于原子或分子周围的光场态密度。在拥有完全光子带隙的光子晶体中，由于在光子带隙的频率范围内不存在光的电磁波模式，自发辐射将被完全禁止。同时，在光子晶体中会出现许多新的效应，如光子-原子限域态的出现、光谱劈裂、自发辐射增强的量子相干效应、非经典衰减和Lamb移动等。本论文以稀土掺杂反蛋白石光子晶体为研究对象，一方面研究不同基质材料，不同稀土离子掺杂浓度的反蛋白石光子晶体的可控制备，另一方面我们研究了不同带隙光子晶体对稀土离子自发辐射速率的调制作用，并在此基础上研究了光子晶体在折射率传感中地应用，具体取得了如下成果：1.通过自组装模板技术结合溶胶-凝胶法成功获得了高度有序，光子带隙可控的YVO4:Dy3+/Eu3+的反蛋白石光子晶体样品。发现当Dy3+/Eu3+离子的发光位置与光子带隙重叠时，其自发辐射速率受到抑制；而Dy3+/Eu3+离子的寿命的变化却不依赖与光子带隙，但相对于参考样品其寿命延长了大约2.5倍。我们得出结论：在弱调制的反蛋白石光子晶体中，其寿命的变化不是来源于局域态密度地改变，而是由于周围介质有效折射率地改变引起。在参考样品中，钒酸根离子和Dy3+离子的强度随温度升高急剧地下降，而在光子晶体中，其强度却变化很小，这是由于反蛋白石特殊的结构（薄壁，大的空隙率）可以有效地抑制离子间的长程能量传递过程。2.将五种折射率相差很小的不同液体渗透到反蛋白样品中，测试其光子禁带位置和Eu3+离子寿命的变化，发现在大折射率材料的光子晶体中，基于荧光寿命作为指标来进行传感，其灵敏度提高了很多，并通过实腔和虚腔模型对结果进行分析，发现当发光中心处在空气中时适合虚腔模型，处在液体环境时适合实腔模型。3.首次在磷酸盐体系中系统地研究并比较了光子晶体对Ce3+（短寿命）和Tb3+（长寿命）的发射光谱和动力学过程的调制。相对于参考样品，我们观察到反蛋白石光子晶体中Tb3+离子的5D4-7F5,5D3-7F5的自发辐射速率都有了很大地抑制。更重要的是我们发现反蛋白石光子晶体中，由于其特殊的空腔结构，Tb3+离子向周围缺陷态的能量迁移，Tb3+离子之间的交叉弛豫和温度猝灭都有了很明显地抑制，并通过基态和激发态标准的位形坐标图来对实验结果进行分析。4.成功制备出不同孔径大小的YVO4:Yb3+，Er3+上转换反蛋白石光子晶体，首先详细研究了光子晶体对其自发辐射地调制，对变温光谱和动力学的研究发现，由于光子晶体特殊结构对发光的调制作用，光子晶体中的非辐射跃迁速率远小于参考样品。通过反蛋白石特殊的结构来提高热扩散速率，进而降低发光中心局域点的温度，有效抑制温度猝灭。5.通过静电相互作用将制备出YVO4:Eu3+反蛋白石光子晶体和用巯基乙酸修饰的CdTe量子点吸附在一起制备出复合材料，通过量子点和稀土离子之间的共振能量传递来实现稀土离子激发谱展宽（450到590纳米），并通过反蛋白石特殊结构来有效的抑制量子点和稀土离子的非辐射弛豫过程，我们发现相对与粉末参考样品，光子晶体中Eu3+离子的发光强度提高了20倍，量子点和稀土之间的能量传递效率达到了47%。更多还原

【Abstract】 The concept of photonic crystals (PCs) has attracted much attention worldwidesince it was first proposed in1987. This kind of long-range order structure makesthe refractive index modulated with periodicity in optical wavelength, which leads tothe formation of photonic stop band (PSB). When the materials satisfy Braggscattering conditions, the light of the specific frequency will be inhibited in the PCsdue to the inhibition of PSB. The spatial periodic modulation of PCs opens up newpossibilities for the development of optoelectronic devices. Among all the specialproperties of the PCs, a very important aspect is modulation of spontaneousemission, when photoluminescence centers were embedded in PCs. According to theFermi gold rules, within the scope of the spontaneous radiation frequency, thespontaneous emission rate is proportional to the photon state density around theatoms or molecules in the weak field category. If the PCs have a complete photonicband gap, the spontaneous emission will be inhibited completely because there is noelectromagnetic wave mode in the frequency range of photonic band gap. At thesame time, there will be many new effects in the PCs, such as the emergence of thephotons-atoms confined state, spectral splitting, spontaneous radiation enhancedquantum coherence effect, non classical damping and lamb shift, etc. In this paper,we studied the lanthanide doped inverse opal PCs. On one hand, we studied thecontrollable preparation of inverse opal PCs of different substrate materials anddifferent rare earth doping concentrations; on the other hand, we studied themodulation effect of the different band gap PCs on the spontaneous radiation rate ofrare earth ions, on the basis of which, the application of PCs is further studied in therefractive index sensing, the findings are listed below:1. The YVO4: Dy3+/Eu3+inverse opal PCs samples with highly ordered, controllable PSBs were successfully prepared through self-assembly template technequecombined with sol-gel method. We found that the spontaneous emission will beinhibited, when the emission bands of Dy3+or Eu3+ions overlap with the PSBs. Thechanges of lifetimes of Dy3+/Eu3+ions are independent on the PSBs, The lifetimes inPC4are prolonged~2.5times in contrast to the reference samples. We conclude thatin weakly coupled PCs, the variation of lifetime is attributed to the change ofeffective refractive index of surrounding medium, instead of the change of localdensity of state. As the temperature increases, the luminescence intensity ofvanadate groups and Dy3+ions decreases quickly, however, the emissions rarelychange in PCs since the special structure of opal (thin wall, large void ratio) caneffectively inhibit the long range energy transfer process among the rare earth ions.2. The five liquids of different refractive index with little differences were infiltratedinto the inverse opal PCs, the shifts of PSBs and the lifetimes of Eu3+ions have beenmeasured. We found that the sensing sensitivity improved largely in PCs materialswith large refractive index, based on the fluorescence lifetime as indicators forsensing. Using the virtual and real cavity model to fit the experimental results, wefound that the virtual cavity model is useful as the luminescence centers are in theair, the real cavity model is valid as the luminescence centers are put into solutions.3. We studied and compared the modulation of phosphace PCs on the emissionspectra and kinctic process of Ce3+(short lifetime) ions and Tb3+(long lifetime) ions.We observed that the transition rate of5D4-7F5,5D3-7F5have been largely inhibited inPCs compared to the reference sample. More importantly, we found that the energytransfer from Tb3+ions to the surrounding defect states, the cross relaxation amongTb3+and the temperature quenching have been inhibited, due to the special cavitystructures of inverse opal PCs, we also analyze the experimental results using theground state and excited state standard configuration coordinate.4. The successful preparation of the different size of YVO4: Yb3+, Er3+upconversioninverse opal PCs was demonstrated. First we study in details the modulation of thePCs on spontaneous emission, temperature-dependent emission spectra anddynamics. Due to the effect of the special structure of inverse opal PCs on spontaneous emission, the nonradiative transition rate of Er3+ions in PCs is far lessthan that in corresponding reference samples. The thermal diffusion rate has beenimproved in the inverse opal structures, the local temperature of the luminescencecenter will be lowered, so the temperature quenching can be effectively restrained.5. The composites combining YVO4:Eu3+inverse opal PCs and mercaptoacetic acidmodified CdTe quantum dots have been successfully prepared through electrostaticinteraction. Through the fluorescence resonance energy transfer from CdTe QDs toEu3+ions, a broad excitation band (450-590nm) was obtained for the rare earthemission. Due to the restrained nonradiative transition of CdTe QDs and rare earthions in the inverse opal PCs, the luminescence intensity of Eu3+ion in PCs wasimproved~20times compared to that in reference sample, and the energy transferbetween quantum dots and rare earth ions reached47%.更多还原