Lin H, Liu C P
State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, P. O. Box 800-211, Shanghai, 201800, China.
Sci Rep. 2021 Mar 23;11(1):6663. doi: 10.1038/s41598-021-85619-2.
We propose a feasible, high-efficiency scheme of primary terahertz (THz) radiation source through manipulating electronic structure (ES) of a metallic film by targeted-designed DC-fields configuration. The DC magnetic field is designed to be of a spatially inhomogeneous strength profile, and its direction is designed to be normal to the film, and the direction of the DC electric field is parallel to the film. Strict quantum theory and numerical results indicate that the ES under such a field configuration will change from a 3D Fermi sphere into a highly-degenerate structure whose density-of-state curve has pseudogap near Fermi surface. Wavefunctions' shapes in this new ES are space-asymmetric, and the width of pseudogap near Fermi surface, as well as magnitudes of transition matrix element, can be handily controlled by adjusting parameter values of DC fields. Under available parameter values, the width of the pseudogap can be at milli-electron-volt level (corresponding to THz radiation frequency), and the magnitude of oscillating dipole can be at [Formula: see text]-level. In room-temperature environment, phonon in metal can pump the ES to achieve population inversion.
我们提出了一种可行的、高效的太赫兹（THz）辐射源初级方案，该方案通过特定设计的直流电场配置来操控金属薄膜的电子结构（ES）。直流磁场设计为具有空间不均匀的强度分布，其方向设计为垂直于薄膜，直流电场的方向与薄膜平行。严格的量子理论和数值结果表明，在这种场配置下，电子结构将从三维费米球转变为一种高度简并的结构，其态密度曲线在费米面附近有赝能隙。这种新电子结构中的波函数形状是空间不对称的，通过调整直流电场的参数值，可以方便地控制费米面附近赝能隙的宽度以及跃迁矩阵元的大小。在可用的参数值下，赝能隙的宽度可以达到毫电子伏特量级（对应于太赫兹辐射频率），振荡偶极矩的大小可以达到[公式：见正文]量级。在室温环境下，金属中的声子可以泵浦电子结构以实现粒子数反转。
