连续区光子束缚态理论与传感应用研究

Trapping or storing light is of great importance for both science and technology. It is the basis of wide-ranging applications for optical communication, quantum computation, and particularly, chemical and biology sensing. A conventional device for confining light is known as optical resonator, in which outgoing waves are completely forbidden. However, recent finding indicate that perfect light trapping can still be achieved even allowed outgoing waves, because of a particular localized state, the bound sate in the continuum (BIC). Utilizing periodic electromagnetic structure that is analogy to a quantum system, the permittivity distribution can be manipulated to support BIC. In this project, we propose to realize BIC in a photonic crystal (PC) system working in the continuum region. Based on a full-wave, 3D coupled-wave theory model that depicts the interaction and couplings between those individual Bloch waves, the BICs can be reviewed from an analytical perspective. We will develop a comprehensive theoretical model to present BIC in both infinite-periodicity and finite-size structures. The intrinsic symmetric and topologic natures of the photonic system will be investigated. In addition, since the optical leakage and reflection on the boundary will degrade light-trapping, we attempt to eliminate them that form a full-space localized BIC. Further, we will investigate novel sensing mechanism by utilizing two kinds of BIC, i.e, symmetric BICs and tunable BICs. The device will be fabrication by using standard semiconductor processes, such as EBL and ICP, on the silicon-on-insulator (SOI) platform. To observe BIC, a reflectivity spectrum measurement system will be constructed by using lock-in amplifier for achieving maximum sensitivity. A demonstration of the refractive index sensing based on BIC will be experimentally presented. We believe our exploring of the BICs will be essential important for understanding the fundamental physics in photonic system, and will boost the application in optical communication and bio/chemical sensing.

如何实现维纳尺度下的光场束缚（light trapping）是光电子领域一个广为关注的问题，它是实现光缓存、光逻辑、光量子器件，及各种生物和化学传感应用的基础。本项目拟利用光子晶体类比量子系统的“原子势场”，通过“连续区光子束缚态（BIC态）”在允许光逃逸情况下实现光场束缚。项目拟研究BIC态的物理规律，澄清光子系统内禀性质如对称性、拓扑特性与BIC态的关系；进而建立精确、高效的理论模型；并探索有限尺度下全空间局域化BIC态的可能性。基于标准半导体工艺，项目拟突破BIC态制备和观测关键技术。应用方面，项目拟利用BIC态在器件面积和稳定性上的优势，探索新型折射率传感机理，并进行实验验证。作为一种不同于传统“微谐振腔”的光场局域化新机制，“连续区光子束缚态”，逐渐成为学术界研究的热点，具有巨大科学意义和广阔应用前景。特别是基于BIC态的传感应用目前尚属空白，极具研究价值。

如何实现微尺度下的光场束缚（light trapping）是光电子领域一个广为关注的问题，它是实现光缓存、光逻辑、光量子器件，及各种生物和化学传感应用的基础。本项目利用光子晶体类比量子系统的“原子势场”，通过“连续区光子束缚态（BIC态）”在允许光逃逸情况下实现光场束缚。项目研究了BIC态的物理规律，澄清光子系统内禀性质如“对称”和“拓扑”性质与BIC态的关系；进而建立精确、高效的理论模型；光子晶体辐射引入的非厄米性质导致了新奇的物理现象，项目发现了一种独特的体费米弧和偏振态半整数拓扑荷现象，体现了非厄米体系独特的拓扑性质。拓扑荷为实现局域化、高Q值BIC态的新机理和新方法。基于标准半导体工艺，项目突破了BIC态制备和观测关键技术，利用拓扑荷合并机理实现了对随机散射鲁棒的高Q谐振态，实测Q值达创纪录的50万。作为一种不同于传统“微谐振腔”的光场局域化新机制，“连续区光子束缚态”在包括集成光源、传感器、量子计算等领域具有巨大科学意义和广阔应用前景。