Wan Zhongjun, Li Qizheng, Yang Hang, He Linzhen, Lu Liangliang, Chen Zi-Yu, Zhang Qingyuan, Hou Yidong, Wu Lili, Liang Houkun
Opt Lett. 2025 May 1;50(9):3050-3053. doi: 10.1364/OL.555169.
High harmonic generation (HHG) in solids holds immense potential for probing ultrafast electron dynamics in crystals, with a much lower threshold compared to its molecular counterpart. In this work, we demonstrate an Au-disk array on a cadmium telluride (CdTe) nanofilm, which generates a local electric field on the surface, enhancing harmonic generation. Compared to a bare CdTe nanofilm, the structured sample exhibits a harmonic strength enhancement of ∼50 times, and the harmonic cutoff order extends from the 23rd to the 32nd. Owing to the flatband dispersion near the Fermi level and the high carrier mobility of CdTe, as well as the field enhancement from the design of a metasurface, the 24th harmonic is observed at an ultra-low laser intensity threshold of 7 GW/cm. This demonstrates a new, to the best of our knowledge, HHG threshold and higher order of harmonics. The HHG of a metastructure with ultra-low threshold overcomes the common problem of material damage seen in traditional metastructures, enabling HHG to be driven by compact and cost-effective pump lasers.
固体中的高次谐波产生（HHG）在探测晶体中的超快电子动力学方面具有巨大潜力，与分子体系相比阈值要低得多。在这项工作中，我们展示了一种碲化镉（CdTe）纳米薄膜上的金盘阵列，它能在表面产生局部电场，增强谐波产生。与裸CdTe纳米薄膜相比，结构化样品的谐波强度增强了约50倍，谐波截止阶数从第23阶扩展到第32阶。由于CdTe在费米能级附近的平带色散和高载流子迁移率，以及超表面设计带来的场增强，在7 GW/cm的超低激光强度阈值下观察到了第24阶谐波。据我们所知，这展示了一种新的HHG阈值和更高阶谐波。具有超低阈值的超结构的HHG克服了传统超结构中常见的材料损伤问题，使得HHG能够由紧凑且经济高效的泵浦激光器驱动。
