Abstract-THz imaging techniques for nondestructive inspections

Kodo Kanwkse,  Takayuki Shibuya, Shin'ichiro Hayashi, Koji Suizu

https://www.sciencedirect.com/science/article/pii/S1631070510000423

We have suggested a wide range of real-life applications using novel terahertz imaging techniques. A high-resolution terahertz tomography has been demonstrated by ultra short terahertz pulses using optical fiber and a nonlinear organic crystal. We also describe a nondestructive inspection system that can monitor the soot distribution in a ceramic filter using millimeter-to-terahertz wave computed tomography. Further, we report on the thickness measurement of very thin films using high-sensitivity metal mesh filter. These techniques are directly applicable to the nondestructive testing in industries.

Abstract- Terahertz-wave parametric gain of stimulated polariton scattering

Yuma Takida, Jun-ichi Shikata, Kouji Nawata, Yu Tokizane, Zhengli Han, Mio Koyama, Takashi Notake, Shin'ichiro Hayashi, and Hiroaki Minamide

https://journals.aps.org/pra/abstract/10.1103/PhysRevA.93.043836

We have experimentally determined the terahertz- (THz-) wave parametric gain of stimulated Raman scattering (SRS) by phonon-polaritons in LiNbO3. Our approach is based on ultrabright THz-wave generation from SRS under stimulated Brillouin scattering suppression with subnanosecond pump pulses. To obtain the frequency dependence of the parametric gain, we measured the crystal-length dependence of the THz-wave output directly using a surface-coupling configuration. We found that the product of the parametric gain and the threshold crystal length is constant throughout the tuning range. Our result provides a physical basis for the design and performance enhancement of SRS-based ultrabright tabletop THz-wave sources for various applications.

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