The mid‐wave infrared (MWIR) spectral region (3–5 µm) is important to a vast variety of applications in imaging, sensing, spectroscopy, surgery, and optical communications. Efficient third‐harmonic generation (THG), converting light from the MWIR range into the near‐infrared, a region with mature optical detection and manipulation technologies, offers the opportunity to mitigate a commonly recognized limitation of current MWIR systems. In this work, the possibility of boosting THG in the MWIR through a metasurface design is presented. Specifically, a 30‐fold enhancement in a highly nonlinear phase‐change material Ge₂Sb₂Se₄Te₁ (GSST) is demonstrated by patterning arrays of subwavelength cylinders supporting a magnetic dipolar resonance. The unprecedented broadband transparency, large refractive index, and remarkably high nonlinear response, together with unique phase‐change properties, make GSST‐based metasurfaces an appealing solution for reconfigurable and ultra‐compact nonlinear devices operating in the MWIR.

中文翻译：

---

基于相变材料的非线性中红外超颖表面

中波红外（MWIR）光谱区域（3-5 µm）对于成像，传感，光谱学，手术和光通信中的各种应用至关重要。有效的三次谐波产生（THG），将来自MWIR范围的光转换为具有成熟的光学检测和操纵技术的近红外区域，为缓解当前MWIR系统普遍公认的局限性提供了机会。在这项工作中，提出了通过超表面设计提高MWIR中THG的可能性。特别是，高度非线性的相变材料Ge ₂ Sb ₂ Se ₄ Te ₁增强了30倍（GSST）通过对支持磁偶极子共振的亚波长圆柱阵列进行图形化演示。前所未有的宽带透明性，大折射率和出色的非线性响应，再加上独特的相变特性，使得基于GSST的超颖表面成为在MWIR中运行的可重构和超紧凑非线性设备的理想解决方案。