Qiao Yue, Chen Jiaqi, Li Zhigang, Liu Yanping, Jiang Shicheng, Liu Wenjun, Yang Yujun, Chen Jigen
Opt Lett. 2024 Jul 15;49(14):3986-3989. doi: 10.1364/OL.531904.
Recent theoretical and experimental findings have demonstrated the minimum characteristic in the harmonic spectrum of bulk MgO crystals subjected to intense laser pulses. However, the dominant mechanism behind this minimum structure is still under debate. This study simulates the harmonic spectrum from a MgO crystal in a linearly polarized laser pulse by solving multi-band semiconductor Bloch equations. The results show that the minimum feature at 20 eV in the MgO harmonic spectra from 1700 and 800 nm laser pulses is due to band dispersion and interference between interband harmonics. Notably, the disappearance of the minimum structure at 14 eV in the harmonic spectrum from the 800 nm laser is attributed to the intensity suppression of higher energy harmonics, caused by decreased electron population at the boundary of the first Brillouin zone in the multi-band case. These findings offer insights into the spectral structure of solid-state harmonics, contributing to the all-optical reconstruction of the crystal band based on its harmonic spectrum.
最近的理论和实验结果表明，在强激光脉冲作用下，块状氧化镁晶体的谐波光谱具有最小特征。然而，这种最小结构背后的主导机制仍存在争议。本研究通过求解多带半导体布洛赫方程，模拟了线性偏振激光脉冲作用下氧化镁晶体的谐波光谱。结果表明，1700纳米和800纳米激光脉冲作用下氧化镁谐波光谱中20电子伏特处的最小特征是由于带间色散和带间谐波之间的干涉。值得注意的是，800纳米激光谐波光谱中14电子伏特处最小结构的消失归因于多带情况下第一布里渊区边界处电子数减少导致的高能谐波强度抑制。这些发现为固态谐波的光谱结构提供了见解，有助于基于谐波光谱对晶体能带进行全光重建。
