Journal of the Korean Society for Nondestructive Testing (비파괴검사학회지)

The Korean Society for Nondestructive Testing (한국비파괴검사학회)
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Modeling of THz Frequency Spectrum via Optical Rectification in THz Time Domain Spectroscopy

테라헤르츠 시간 영역 분광의 광정류시 발생하는 테라헤르츠 스펙트럼 모델링

  • Published : 2008.04.30
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Abstract

In recent years, gradually increasing interest has been directed to the use of terahertz technology in nondestructive testing and non-invasive measurements, and terahertz time domain spectroscopy (THz-TDS) has become a key technology in such applications. This paper deals with the terahertz pulse generation from cadmium telluride via optical rectification process of femto-second infrared laser pulses. The measured terahertz spectrum is compared with the result of model calculation based on space-time domain nonlinear Maxwell equations for coherent frequency mixing process. The propagation process of terahertz and infra-red pulses in the material as well as the surface interference and free space diffraction effects are also considered. The experimental results are in good agreements with the calculated spectrum.

최근 비파괴 검사를 위한 테라헤르츠 전자기파 기술에 대한 관심이 높아지고 있으며 특히 비파괴검사에서 많은 응용이 기대된다. 테라헤르츠 시간 영역 분광법은 이러한 테라헤르츠 기술에 핵심이 되는 기술로 많은 실험이 이루어지고 있다. 본 논문에서는 테라헤르츠 시간 영역 분광에서 비선형 전광물질을 이용하는 광정류 방식을 통해 발생된 테라헤르츠 전자기파 스펙트럼이 비선형 맥스웰 방정식의 해와 실험에 의해 결정되는 흡수, 회절, 표면간섭 효과 등을 고려한 본문의 모델을 통하여 예측가능하며 실제 티타늄:사파이어 레이저 펄스를 $400{\mu}m$ CdTe에 조사하여 발생된 테라헤르츠파 주파수 스펙트럼의 측정 결과와 비교하여 매우 유사하다는 사실을 보여준다. 이를 통하여 본문에서 소개된 모델은 다른 전광물질을 통해 발생된 테라헤르츠 스펙트럼에도 확장되어 적용 될 수 있다.

Keywords

References

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