摘要
虽然目前国际上对于太赫兹这个崭新的学术领域给予了极大的关注,但是由于对这个频段电磁波的产生和探测都具有极大的困难,所以到目前为止,人们对于这个领域所做的工作依然十分有限。相对于太赫兹波而言,光波段电磁波的波长过短,而微波波段的电磁波的波长又过长,所以这两种已经十分成熟的技术无法直接应用于太赫兹的领域。但随着超短激光脉技术的发展,太赫兹波技术在很多领域得到了大大的发展。
过去几年,Drude-Lorentz方法是一种被广泛应用于产生太赫兹波的理论计算方法。本论文在Drude-Lorentz理论的基础上,应用半导体的边界条件,对太赫兹波作用在半导体表面的太赫兹波辐射公式进行了推导,研究模拟了半导体表面辐射的太赫兹波的各种特性,结果表明,在半导体表同上改变一些激发的条件,可以在半导体表面产生更强的太赫兹波的辐射。又在半导体表面为平面的基础上,研究了半导体表面为周期矩形时太赫兹的辐射情况,研究模拟发现,与半导体表面为平面的情况相比,可以得到成倍数增长的太赫兹波。本论文最后提出了一个实验方案,对半导体表面为周期矩形半导体表面辐射的情况的参数进行了优化设计,在最优化设计的情况下,要保证在周期半导体表面情况下太赫兹的辐射达到最强,必须使半导体表面为平面情况下的太赫兹波达到最强,这是由于周期矩形半导体表面看作是一系列半导体表面的叠加。
本论文提出了一个增强太赫兹波源的设计思想,探讨了这种方法的优势,为太赫兹的发展增加了一种思路。
Terahertz signals were until recently an almost unexplored area of research due to the difficulties in generation and detection of electromagnetic fields at these wavelengths. Neither optical nor microwave techniques are directly applicable in the Terahertz range since optical wavelengths are too short and microwave wavelengths are too long compared to Terahertz field wavelengths. As The development of ultrafast optical techniques, the Terahertz technique has been boosted as a new area of research in many important applications.
In the past year, Drude-Lorentz theory provides a normal way to calculate the Terahertz waves from photoconductor. In this paper, we present a theoretical framework allow us to investigate the radiation of Terahertz on the semiconductor surface. The formulation is based on Drude-Lorentz theory resulting upon imposing an appropriate boundary condition. Furthermore, we discuss the situation that the semiconductor surface is plane, under the circumstance, we use matlab to simulate the emission process, An increase in eimission power is observed when we change some parameters.We also have discussed the situation that the semiconductor surface is not completely plane but periodic rectanglar grooves, we find that the amplitude of the THz wave is increased linearly with increasing number of periods of the rectangular grooves. To ensure THz emission power reach peak when the semiconductor surface is periodic rectanglar grooves,we must ensure THz emission power also reach peak in the situation that the semiconductor surface is plane.
To sum up, we give a design idea to improve the power of THz radiation, and we discuss the advantages that this precept has brings. It’s important to characterize the THz wave from the periodic rectangular grooves.
引文
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