• Title/Summary/Keyword: 테라헤르츠 분광학

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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)

  • Lee, Kang-Hee;Yi, Min-Woo;Ahn, Jea-Wook
    • Journal of the Korean Society for Nondestructive Testing
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    • v.28 no.2
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    • pp.119-124
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    • 2008
  • 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.

Fs-THz beam line electron accelerator of pulse modulator design and fabrication (펨토 초-테라헤르츠 빔 라인용 펄스 모듈레이터의 설계와 제작)

  • Son, Yoon-Kyoo;Kwon, Sei-Jin;Suh, Jae-Hak;Jang, Sung-Duck;Kang, Heung-Sik;Lee, Kyung-Tae;Ro, Sung-Chae
    • Proceedings of the KIEE Conference
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    • 2008.07a
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    • pp.1322-1323
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    • 2008
  • 기존의 펨토 초 레이저를 이용하여 발생시킨 테라 헤르츠 광원의 한계를 극복하기 위하여 대용량의 가속기를 이용한 테라 헤르츠 광원의 발생에 관한 연구가 활발히 진행되고 있다. 포항방사광 가속기연구소에서도 펨토 초 테라 헤르츠 빔을 이용한 분광학적인 방법을 사용하여 단백질 접힘과 DNA-단백질 간 상호작용, 화학적, 생물학적인 반응 동력학 등에 관한 연구와 영상 기술개발 등을 할 계획을 가지고 펨토초 테라 헤르츠 빔 라인을 건설 중에 있다. 펨토 초-테라 헤르츠 빔 라인의 마이크로웨이브를 가속하는 장치에 사용되는 전원장치의 설계와 제작 및 시험과정을 외국기술에 의존하지 않고 순수 국내기술로 실현하였다. 본 논문에서는 펄스 모듈레이터의 설계와 실험결과를 보이고자 한다.

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Differential Transmission Spectra of Terahertz Metamaterial Resonances for Sensing Microorganisms (미생물에 의한 테라헤르츠 메타물질의 공명주파수 변화)

  • Park, S.J.;Ahn, Y.H.
    • Korean Journal of Optics and Photonics
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    • v.27 no.6
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    • pp.229-232
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    • 2016
  • Metamaterials operating in the terahertz frequency range show promising potential for use in highly sensitive microbial sensors that are capable of effectively detecting microorganisms in the ambient environment. We were able to detect extremely small numbers of microorganisms by measuring the differential transmission spectra (DTS) of the metamaterial resonances. This was possible because their sizes are on the same scale as the microgaps of the terahertz metamaterials. DTS depend critically on the number of microorganisms placed in the gap area, and their dielectric constant. In addition, these metamaterial microbial sensors are reusable, because the microorganisms can be completely removed by fungicide solution. Finite-difference time-domain simulations successfully reproduce our experimental data.

The Doping Concentration and Physical Properties Measurement of Silicon Wafer Using Terahertz Wave (테라헤르츠파를 이용한 실리콘 웨이퍼의 도핑 정도와 물리적 특성 측정에 관한 연구)

  • Park, Sung Hyeon;Oh, Gyung Hwan;Kim, Hak Sung
    • Journal of the Korean Society for Nondestructive Testing
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    • v.37 no.1
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    • pp.1-6
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    • 2017
  • In this study, a terahertz time domain spectroscopy (THz-TDS) imaging technique was used to measure doping concentration and physical properties (such as refractive index and permittivity) of the doped silicon (Si) wafers. The transmission and reflection modes with an incidence angle of $30^{\circ}$ were employed to determine the physical properties of the doped Si wafers. The doping concentrations of the prepared Si wafers were varied from $10^{14}$ to $10^{18}$ in both N-type and P-type cases. Finally, the correlation between the doping concentration and the power of the THz wave was determined by measuring the powers of the transmitted and reflected THz waves of the doped Si wafers. Additionally, the doped thickness, the refractive index, and permittivity of each doped Si wafer were calculated using the THz time domain waveform. The results indicate that the THz-TDS imaging technique is potentially a promising technique to measure the doping concentration as well as other optical properties (such as the refractive index and permittivity) of the doped Si wafer.

Terahertz Characteristics of D2O and H2O Mixtures (테라헤르츠 분광학을 이용한 중수(D2O)와 경수(H2O) 혼합물의 특성연구)

  • Chong, Joong-Gun;Son, Joo-Hiuk
    • Korean Journal of Optics and Photonics
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    • v.19 no.6
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    • pp.435-438
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    • 2008
  • D2O, which is used in nuclear power generation, is slightly different from $H_2O$. $D_2O$ consists of deuterium (D), which is an isotope of hydrogen (H) and has one more neutron than H. $D_2O$ is heavier by about 11% than $H_2O$, and $D_2O$ is present in water in natureat about 0.002%. Its melting point and boiling point are $3.81^{\circ}C$ and $101.42^{\circ}C$, respectively. $D_2O$ is harmful to the human body if it replaces water in the human body by more than $25%{\sim}50%$. We have measured the index of refractive and power absorption of 0%, 25%, 50%, 75%, and 100% of $D_2O$ in $H_2O$ using terahertz time-domain spectroscopy, and we have found that the refractive index decreases and power absorption also decreases as the concentration of $D_2O$ increases.