Abstract-Visualization of the internal field in the GaAs-based solar cell under its operating condition with Terahertz radiation

K. Miyagawa, M. Nagai, C. Kim,  H. Akiyama, Y. Kanemitsu, M. Ashida

https://ieeexplore.ieee.org/document/8510084

We demonstrated the visualization of the internal field in a GaAs-based solar cell under its operating condition with evaluating the first half-period of the terahertz (THz) wave emitted by the simultaneous excitation with the weak ultrashort optical pulse and continuous light. We observed the reduction of the internal field with increasing the intensity of the continuous light, which is relevant to the solar cell performance.

Abstract-THz artificial dielectric isolator

R. Mendis,  M. Nagai,   W. Zhang,   D. M. Mittleman

http://ieeexplore.ieee.org/document/8066918/

We experimentally demonstrate an isolator suitable for the THz spectral regime. The isolator is designed by combining a polarizing beamsplitter with a quarter-wave plate, both based on the same artificial-dielectric technology. The artificial-dielectric medium comprises of a stack of 30 μm thick metal plates that form an array of parallel-plate waveguides. The isolator exhibits an isolation of 52 dB with an insertion loss less than one dB, at a frequency of 0.46 THz, which rivals the performance of commercially available Faraday isolators for optical wavelengths.

Abstract-Electrical transport properties of (La,Pr,Ca)MnO3 nanowires investigated using terahertz time domain spectroscopy

T. V. A. Nguyen1,a), A. N. Hattori1,2, M. Nagai3, T. Nakamura1, M. Ashida3 and H. Tanaka1,b)
a) Current affiliation: Department of Materials Science and Engineering, Graduate School of Engineering, Osaka University, Japan
b) Author to whom correspondence should be addressed. Electronic mail: h-tanaka@sanken.osaka-u.ac.jp
J. Appl. Phys. 119, 125102 (2016); 
http://dx.doi.org/10.1063/1.4944601

The electrical transport properties of a 100-nm-width (La,Pr,Ca)MnO3nanowire sample were investigated using terahertz (THz) time domain spectroscopy. When the electric field of incident THz pulses was parallel to the nanowires, we obtained their intrinsic THz conductivity. The temperature-dependent dcconductivity and metallic fraction were simultaneously estimated by analyzing the THz conductivity using a metal-insulatorcomposite model. The evaluated dc conductivity closely reproduced that measured by electrical probe measurement. The metallic fraction showed the evolution of electric domains from the metallic state at temperatures below 100 K to the insulating state at temperatures above 150 K through a coexistence region, which was in consistence with the phase-separated scenario.