Abstract-Terahertz-wave generation devices using electro-optic polymer slab waveguides and cyclo-olefin polymer clads

Takahiro Kaji, Yukihiro Tominari, Toshiki Yamada, Shingo Saito, Isao Morohashi, and Akira Otomo

Fig. 2 Schematic illustration of the experimental setup used for terahertz (THz) time-domain spectroscopy (THz-TDS). A pump beam was focused onto the EO polymer slab waveguide device using two orthogonally arranged cylindrical lenses (f = 100 mm and f = 12 mm). The double arrows show the polarization directions for the optical pulses. The inset shows the infrared optical microscope image of the end face of the EO polymer slab with a 1.56 μm pump.

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-26-23-30466

We fabricated terahertz (THz) wave generation devices using electro-optic (EO) polymer slab waveguides and cyclo-olefin polymer (COP) clads with very small absorption loss of the THz waves based on a novel device fabrication procedure involving bonding of the poled EO polymer layer to the COP substrates. We demonstrated THz wave generation from the EO polymer slab devices using a 1.55 µm-band femtosecond fiber laser and evaluated the THz wave generation properties of the devices. Our results will lead to the development of compact, highly efficient, and ultrabroadband THz devices using EO polymers.

© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Terahertz spectral change associated with glass transition of poly-ε-caprolactone

Marina Komatsu^1,a), Maya Mizuno², Shingo Saito³, Kaori Fukunaga² and Yoshimichi Ohki^1,4,b)
http://scitation.aip.org/content/aip/journal/jap/117/13/10.1063/1.4916746
1 Department of Electrical Engineering and Bioscience, Waseda University, Shinjuku, Tokyo 169-8555, Japan
2 Applied Electromagnetic Research Institute, National Institute of Information and Communications Technology, Koganei, Tokyo 184-8795, Japan
3 Advanced ICT Research Institute, National Institute of Information and Communications Technology, Koganei, Tokyo 184-8795, Japan
4 Research Institute for Materials Science and Technology, Waseda University, Shinjuku, Tokyo 169-8555, Japan


a) mkomatsu@toki.waseda.jp
b) yohki@waseda.jp
J. Appl. Phys. 117, 133102 (2015); http://dx.doi.org/10.1063/1.4916746

We measured absorption spectra of unidirectionally stretched poly-ε-caprolactone (PCL) film in a range from 0.3 to 3.6 THz at temperatures from 10 to 300 K. Several absorption peaks were observed, when the electric field of THz waves was set in directions parallel and perpendicular to the stretching direction. The absorption bandwidths became significantly broad at around 200 K and above at least in two specific peaks. This temperature is close to the glass transition temperature of PCL. Further, it is shown by quantum chemical calculations that all the peaks obtained experimentally originate in skeletal vibrations of PCL. Therefore, it has become clear that a specific feature appears in the THz absorption spectrum of PCL associated with its glass transition.