外场调控下超常材料的类度规相变及光爆发的研究

A "metric-signature-transition-like" (MSTL) in the optical system, i.e., a transformation from a hyperbolic material to an ordinary dielectric, is a research focus in photonics. During the MSTL in an optical material, a "big flash" event can occur. The "big flash" has many similarities with the cosmological "big bang". The study of MSTL not only can bring a new way for the control of light, but also can be used to mimic the metric signature transition in the general relativity theory. Based on our early work, firstly we will design and fabricate a metamaterials which can be realized the MSTL with an external magnetic control. Then, we will try to understand the physical mechanism for this MSTL process by studying the optical properties, the electromagnetic field distribution, and the evolution of the eigen-states near the critical point of the phase transition. After that, we hope to make clear where the photons energy comes from and how the energy is transformed in the process of big flash, based on the investigation on the dynamical processes in the time domain and the characteristics of the spectra in the frequency domain, as well as the evolution of the density of states, during the big flash process. Also, we want to establish an effective and concise theory to describe the MSTL and the big flash processes. Additionally, we will study how to control light via MSTL, which may have great potential applications for the control of light in the miro-nano structures.

光学体系中的一种"类度规相变"，即双曲介质向普通介质的转变，是近年来国际上的一个研究热点。光学材料在类度规相变时，会出现奇异的"光爆发"现象，类似于宇宙学中的"宇宙大爆炸"。对这种类度规相变的研究，不仅可以增加人们调控光的途径，而且也可以用来类比和验证广义相对论中的度规相变。基于申请人前期的工作基础，本课题拟设计和制备一种在外磁场调控下可以实现类度规相变的超常材料，并通过研究该超常材料在相变临界点附近的光学性质、电磁场分布和本征模式演化等方面的特点，理解这种超常材料中类度规相变的物理机制；通过研究光爆发时的动态时域特征和频谱特性，结合超常材料在相变过程中态密度的变化规律，理解光爆发的能量来源和能量转化的途径。我们希望找到一个有效而简洁的理论描述类度规相变和光爆发的物理过程。此外，我们还将研究利用类度规相变调控光，探讨其在微纳结构光调控中的潜在应用。

本课题深入研究了双曲介质这种具备特殊色散关系的新型超常材料的奇异光学特性，并在光传输调控、自发辐射调控、类度规相变、光爆发等多个方面进行了研究，取得了许多重要成果。在科学上，我们创新了理论方法，突破了以往仅在频域研究双曲介质的定态方法。我们提出并把握住了真实双曲介质最核心的两个因素：“材料色散”和“周期结构效果”。使用我们提出的理论分析方法，不仅能澄清以往人们对双曲介质某些性质的错误认识（一些违反基本物理限制（因果律）的问题），也提供了一种强大而有效的工具来理解和认识真实双曲介质的若干实验结果，为进一步深入研究和应用双曲介质夯实了基础。在应用前景上，我们的研究进一步拓展了双曲介质的潜在应用价值，比如双曲介质调控和增强自发辐射，双曲介质的类度规相变及光爆发，双曲透镜的远场超分辨等。