Development of ultra high sensitive terahertz imaging system

在我们的项目中，太赫兹波继续扩大其应用范围如下。由于缺乏对隐藏在邮件信封中的非法药物进行非破坏性检查的技术，导致这类药物被自由地走私跨越国际边界。我们已经开发出了一种太赫兹成像的基本技术，通过引入成分空间模式分析^[2]，可以探测和识别隐藏在信封中的毒品。目标的空间分布和组成，获得从太赫兹多光谱透照图像，使用可调谐太赫兹波源测量的吸收光谱。我们进一步演示了利用二维电光太赫兹成像技术对化学物质的成分空间模式进行分析，该技术可以捕获实时太赫兹图像^[3]。通过改变泵浦光的光学延迟，CCD相机记录时间相关的太赫兹图像。在0.1和1.0 THz之间测量多光谱图像和光谱数据集;清楚地确定了化学成分，空间分布和浓度差异。另一方面，为了检测大规模集成电路（LSI）中的电气故障，我们开发了激光太赫兹发射显微镜（LTEM），它可以记录样品在飞秒激光脉冲激发下的太赫兹发射振幅图^[4]。当芯片被激光束扫描时，清晰的二维太赫兹发射图像被记录下来。损伤芯片的LTEM图像显示出与正常芯片不同的图案。此外，通过调制IC芯片的输入信号，可以跟踪信号线。这些结果表明，LTEM可以成为一个有用的工具，检测和监控集成电路的质量。作为演示，我们成功地获得了零偏压条件下的MOSFET样品的太赫兹发射图像。

In our project, THz-waves continue to broaden their range of applications as following. The absence of non-destructive inspection techniques for illicit drugs hidden in mail envelopes has resulted in such drugs being freely smuggled across international borders. We have developed a basic technology for THz imaging which allows detection and identification of drugs concealed in envelopes by introducing the component spatial pattern analysis^2. The spatial distribution and the composition of the targets are obtained from THz multispectral transillumination images, using absorption spectra measured with a tunable THz wave source. We further demonstrated a component spatial pattern analysis of chemicals using 2-dimensional electro-optic THz imaging which can capture real-time THz images^3. By changing the optical delay of the pump beam, the CCD camera records time-dependent THz images. The multispectral images and the spectral data set were measured between 0.1 and 1.0 THz ; the chemical composition, the spatial distribution, and the difference in concentration were clearly determined. On the other hand, for inspecting electrical failures in large scale integration circuit (LSI), we developed the laser-THz emission microscope (LTEM), which records the map of THz emission amplitude in a sample upon excitation with fs laser pulses^4. Clear two-dimensional THz-emission images of the IC chip are recorded as the chip is scanned with laser beam. The LTEM images of damaged chips show different patterns from those of normal chips. Also, by modulating the input signal of the IC chip, the signal lines can be traced. These results suggest that the LTEM could become a useful tool for inspecting and monitoring IC quality. As a demonstration, we succeeded in obtaining the THz emission image of a MOSFET sample under zero bias condition.