基于氧化钼薄膜的光控太赫兹传输特性研究

本文采用热蒸发法制备了沉积在硅片上的200nm 氧化钼(MoO₃)的太赫兹调制薄膜。 在室温条件下,通过傅里叶光谱仪和太赫兹时域光谱系统(THz-TDS)技术,研究了MoO₃薄膜在不同激励光功率下的太赫兹传输特性。提出了薄膜重要光学参数的提取模型,利用透 射式太赫兹时域光谱技术测量了薄膜的时域信号,分别计算了太赫兹波在薄膜中的透过率及 调制效率及薄膜的复介电常数变化。结果表明,在980 nm激光器条件 下,随着激光器功率 的提高,MoO₃薄膜的太赫兹调制深度逐渐增加。在激光功率为266 mW时,在0.26 THz处 透过率达到最低为61%,调制效率(Modulation factor)达到最高为10%。通过分析MoO₃薄膜 的复介电常数及载流子密度变化,得出了激发生成的载流子浓度的提高导致介电常数的改变 , 增强了薄膜的导电性,从而减低了太赫兹波在薄膜中的透过率的结论。为MoO₃薄膜应用在 太赫兹波段调制领域提供了实验数据。

Investigation of optical controlled terahertz transmission characteristics based on molybdenum oxide films

In this paper,200nm molybdenum oxide (MoO₃) terahertz modulation film deposited on silicon wafers were prepared by thermal evaporation.The terahertz modulation characteristics of MoO_3films under different excitation optical powers were s tudied by Fourier spectroscopy and terahertz time-domain spectroscopy (THz-TDS) at room temperature.The important optical parameters extraction model of thin film is p roposed.The time-domain signal of thin film is measured by transmission THz time-domain sp ectroscopy. The transmittance and modulation efficiency of THz wave in film and change of co mplex dielectric constant of MoO_3film are calculated respectively.The results show that the terahertz modulation depth of MoO_3film increases with the increase of laser p ower with the wave length of 980nm.The minimum transmittance achieved 61% and the maximum modulation factor achieved 10% under 266mW laser power at 0.23THz.Analyzing th e complex dielectric constant and carrier density of MoO_3film shows that the ex citation of carriers led to the change of dielectric constant,enhance the conductivity of t he film,and reduce the transmittance of THz wave in the film.The experimental data are prov ided for the application of MoO_3film in terahertz band modulation.