超表面中红外上转换成像研究取得进展

As an important atmospheric transmission window, the mid-infrared band plays a key role in fields such as biomedicine and environmental monitoring. Recently, the Xi'an Institute of Optics and Fine Mechanics of the Chinese Academy of Sciences has made progress in the field of metasurface mid-infrared nonlinear frequency upconversion imaging.

Using thin film lithium niobate as a nonlinear optical platform, the research team proposed a nonlinear frequency upconversion method based on quasi-guided mode control. This method introduces quasi-guided mode resonance through Brillouin zone folding to construct a stable high-quality factor resonance mode within a wide wavevector range. It further utilizes the strong coupling effect between quasi-guided mode and guided mode resonance to expand the mode matching range in a single guided mode resonance system, so that different resonance modes can effectively enhance nonlinear effects. Combined with the resonance control capability within a wide wavevector range, this method significantly expands the tuning range of frequency conversion and achieves simultaneous improvements in conversion efficiency and spectral tunability.

基于上述方法，团队搭建了薄膜铌酸锂中红外频率上转换成像系统，成功实现了低光强连续波4.33μm中红外信号的和频上转换成像。通过调节近红外泵浦波长，团队验证了泵浦侧共振调控能力及其对非线性转换过程的影响，结合色散分析进一步证明了宽带可调谐中红外频率转换成像的应用潜力。

该研究将非局域超表面的调控能力拓展至连续波非线性频率转换领域，不仅为小型化、低成本、高灵敏度的中红外探测技术提供了新的技术路径，更凭借该技术的片上集成潜力，在气体检测、环境监测、生物医学成像、集成光子传感等场景展现出广阔的应用前景。

相关研究成果发表在《激光与光子学评论》（Laser & Photonics Reviews）上。

Paper link

超表面频率上转换示意图

Metasurface frequency upconversion imaging results