铁电/反铁电光子晶体及其光子带隙的宽调控机理研究

Ferroelectric and antiferroelectric materials have been widely used for tunable-bandgap photonic crystals due to its remarkable field-modulation effect. The current photonic crystals that based on ZnO(MgO)/ferroelectric thin films, for example, suffer from problems such as lattice mismatch, incompatibility of preparation processes, serious diffusion through interfaces and narrow adjustable range. In this proposal, the high-permittivity-tunability PLZT ferroelectric and PLZST antiferroelectric ceramic targets with high density will be fabricated by the hot-press sintering approach, and subsequently the wide-bandgap- tunability PLZT/PLZST photonic crystals consisting of PLZT and PLZST with similar composition and matched lattices, whose refractive index is able to be tuned reversely, can be easily deposit on quartz glass substrates via the pulsed laser deposition process, due to the ideal process compatibility. The transmission spectrum, the attenuation rate, and the bandgap adjustment rate under electric fields will be investigated, the regulation mechanism of electric field on the ferroelectric/antiferroelectric photonic crystal adjustable bandgap will be explored, and the devices based on the ferroelectric/antiferroelectric photonic crystals will be designed. Taking advantages of the opposite responses of dielectric constants in the ferroelectric and antiferroelectrics with the same electric field, as well as the co-effects of significant changes in lattices and dielectric constant when phase transition is induced by an electric field, the photonic crystals with wide-bandgap-tunability and impressive adaptability can be achieved by designing structures of the electrodes. The project will promote the investigation in novel photonic crystals and optical devices.

铁电和反铁电材料由于其显著的电场调制效应被用于可调带隙光子晶体研究。针对现有ZnO（MgO）/铁电薄膜结构光子晶体存在材料晶格常数不匹配、制备工艺不兼容、界面扩散严重和单一铁电相可调范围窄等问题， 项目采用热压烧结工艺制备高致密度、介电常数可调率高的PLZT铁电和PLZST反铁电陶瓷靶，通过脉冲激光沉积法在石英玻璃衬底上制备组分相近、晶格匹配、工艺兼容、折射率反向变化、带隙宽可调的新型PLZT/PLZST光子晶体，研究其在电场作用下的透射谱和带隙调整率，探索铁电/反铁电光子晶体带隙宽可调的物理机制，设计新型铁电/反铁电光子晶体器件模型。项目利用铁电、反铁电材料在电场作用下介电常数反向可调及PLZT/PLZST组分相近的特点，结合电场诱导相变点处晶格常数突变和介电常数剧变的双重效应，研究铁电/反铁电光子晶体，可满足光子晶体带隙宽可调的应用要求，对研究新型光子晶体及光电子器件有很好的促进作用。

项目对PLZT与PLZST陶瓷靶材进行了制备、对脉冲激光沉积系统沉积高质量PLZT与PLZST的薄膜进行探索、并深入研究了PLZT与PLZST一维光子晶体的带隙调控。分别通过热压烧结和普通固相烧结工艺制备出了致密度高、介电常数可调率高的PLZT铁电和PLZST反铁电陶瓷靶，利用脉冲激光沉积系统在N:STO衬底上制备出了组分相近、晶格匹配、工艺兼容、折射率反向变化、带隙宽可调的新型PLZT/PLZST光子晶体，并研究该一维光子晶体在电场作用下的透射谱变化及带隙调整率，探索铁电/反铁电光子晶体带隙宽可调的物理机制，实现了新型铁电/反铁电光子晶体器件模型。.热压烧结工艺制备的PLZT陶瓷具有更致密和均匀的微观结构，更低的矫顽场和更高的相对介电常数，用其作为脉冲激光沉积镀膜的靶材料可以得到元素均匀分布并且具有更好铁电性的薄膜材料；另一方面，PLZST普通烧结的靶材的没有其他杂相的存在，晶粒尺寸均一性更好，反铁电性和介电性能均优于热压烧结的靶材，可作为制备PLZST薄膜的陶瓷靶材使用。.通过研究薄膜制备工艺，得到PLZT薄膜的最佳工艺参数为沉积氧压30Pa，沉积温度750℃，退火氧压50Pa，粗糙度约为0.5nm，平均反射率高达23%；PLZST薄膜的脉冲激光沉积工艺的最佳沉积温度是700ºC，最佳退火氧压是0.5mbar，退火时间是30min。.电场作用下折射率的增加可以合理解释PLZT/PLZST/PLZT一维光子晶体带隙可调现象。带隙中心波长偏移量12 nm对应的PLZT折射率的变化率为0.92%，实验结果表明，在电场强度为1×10^4 V/mm的直流电场作用下，PLZT薄膜的折射率的变化率接近了1.0%。本项目的研究结果对铁电/反铁电薄膜以及一维光子晶体及器件的制备工艺有重要的指导意义，对铁电/反铁电光子晶体带隙的电场调控机理研究有很好的促进作用。