带宽对平顶高斯宽带激光传输特性的影响

研究了横向分布为平顶高斯模式的宽带激光在自由空间的传输特性,分析了频带宽度对其强度分布的影响。首先推导了平顶高斯模式宽带激光的每一频率分量在自由空间的传输公式,然后将频率域的传输公式通过傅里叶变换得到时间域的传输公式。基于推导的公式通过数值算例给出了不同频带宽度激光光束的强度分布结果,详细分析了空间模式的变化和时空耦合现象。研究结果表明:随着传输距离增大,平顶高斯空间模式趋于高斯分布。同时随着带宽增大,平顶高斯模式宽带激光表现出更强的时空耦合现象,并导致其空间横向分布发生明显变化。变化的主要特征为波前的强度分布随带宽增大而变窄,波后的强度分布则随带宽增大而远离轴中心向外扩展。     

Simulations of monolayer SiC transistors with metallic 1T-phase MoS2 contact for high performance application

We preform a first-principles study of performance of 5 nm double-gated (DG) Schottky-barrier field effect transistors (SBFETs) based on two-dimensional SiC with monolayer or bilayer metallic 1T-phase MoS₂ contacts. Because of the wide bandgap of SiC, the corresponding DG SBFETs can weaken the short channel effect. The calculated transfer characteristics also meet the standard of the high performance transistor summarized by international technology road-map for semiconductors. Moreover, the bilayer metallic 1T-phase MoS₂ contacts in three stacking structures all can further raise the ON-state currents of DG SiC SBFETs in varying degrees. The above results are helpful and instructive for design of short channel transistors in the future.