Novel Ferroelectric Photonic Band-Gap Structures: a Feasibility Study

光子带隙是当材料以周期性的方式形成图案时产生的，通常是通过在微米尺度上钻一个周期性的孔图案。在这种周期性图案的介质中，光的特性发生了巨大的变化，某些特定波长的相互作用变得非常强。本试点研究的创新之处在于将光子带隙图图化与高度非线性外延单晶铁电材料以波导形式结合在一起，从而在横向图图化的基础上增加了光的垂直限制。有了这样的组合，我们可以设想在光学设备效率方面取得巨大的进步，这反过来又将允许在小型化设备格式的光通信中更快的数据传输和处理速度。在这项可行性研究中需要回答的一个关键问题是，铁电波导层能否以足够高的光学质量和足够低的光损耗生长，以证明理论预测的非线性光学效应的增强。考虑到概念验证，我们选择在众所周知的铌酸锂/钽酸锂非线性光学系统中演示一些简单的关键器件。我们试图证明，通过液相外延和熔融外延生长，定制设计和专用的高质量薄膜外延生长将产生后续光子带隙图片化和新器件演示所需质量的材料。在为期一年的研究结束时，这将为涉及更广泛的更奇特的材料和更复杂的设备格式的完整计划奠定基础。据我们所知，这是第一次将光子带隙工程中令人兴奋的新进展与高度非线性铁电外延层相结合的项目。由于华威大学和布里斯托尔大学的团队之间的合作，我们在实现这个为期一年的计划的目标方面处于独特的地位，这结合了他们各自在材料生长和表征以及光学器件设计，制造和测试方面的专业知识。

A photonic band gap is created when a material is patterned in a periodic fashion, typically by drilling in a periodic pattern of holes on a scale of microns. The properties of light in this periodically-patterned medium are vastly changed, with interactions at some specific wavelengths becoming very much stronger. The adventure and innovation in this pilot study is in the combination of photonic band gap patterning with highly nonlinear epitaxial single-crystal ferroelectric materials in a waveguiding format, thus adding vertical confinement of light to the lateral patterning. With such a combination,we can conceive of making massive gains in optical device efficiency which, in turn, will allow faster speeds of data transfer and processing in optical communications in miniaturised device formats. A key question to answer in this feasibility study is whether ferroelectric waveguiding layers can be grown with sufficiently high optical quality and sufficiently low optical loss to demonstrate the enhancements in nonlinear optical effects predicted by theory. With proof of concept in mind, we have chosen to demonstrate a number of simple key devices in the well-known lithium niobate/lithium tantalate nonlinear optical system. We seek to show that custom-designed and dedicated epitaxial growth of high-quality films by both liquid phase epitaxy and epitaxial growth by melting will yield material of the necessary quality for subsequent photonic band-gap patterning and novel device demonstration. This will set the platform for a full programme involving a wider range of more exotic materials and more elaborate device formats at the end of this one-year study. To our knowledge, this is the first time that such a programme to combine the exciting new advances in photonic band-gap engineering with highly nonlinear ferroelectric epitaxial layers has been undertaken. We are uniquely placed to achieve the aims of this one-year programme because of the collaboration between groups at Warwick and Bristol, which combines their respective expertise in materials growth and characterisation and optical device design, fabrication and testing.