光电导天线太赫兹辐射研究

Research of Terahertz Wave Radiation from Photoconductor Antenna

利用超短激光脉冲触发光电导天线产生太赫兹波是目前研究比较深入,同时得到广泛采用的一种太赫兹波源。电流瞬冲模型能较好地解释光电导天线辐射太赫兹波的机理,并且与实验相吻合,因而被普遍接受。影响光电导天线的因素有材料性质、偏转电压、激光脉冲宽度和单脉冲能量等,其中激光脉冲宽度和激光脉冲能量对太赫兹辐射有很重要的影响。材料中的光生载流子寿命对辐射也有一定的影响。当改变这些参数时,辐射的太赫兹波有不同的特性变化。此外,逐步增大激光脉冲能量,会发现辐射的太赫兹波强度存在一个饱和特性。

Photoconductor antennas irradiated by ultrashort laser pulses can emit electromagnetic waves at the terahertz （THz） bandgap, which has been studied extensively and used widely as a terahertz source. It can be described by the current-surge-model, and it agrees well with the experiments. There are many factors that can affect the radiation, such as photoconductor material characters, bias voltage, laser pulse width and energy, and so on. The laser pulse width and energy make important effect on the terahertz wave. The lifetime of carriers in the photoconductor also has an impact on the terahertz wave. The characteristic of radiated terahertz wave has different diversification when the parameters are changed. The intensity of terahertz waves tends to saturate with the increase of laser pulse energy.