Showing posts with label H. Kitahara. Show all posts
Showing posts with label H. Kitahara. Show all posts

Tuesday, October 11, 2016

Abstract-Terahertz Sub-Nanometer Sub-Surface Imaging of 2D Materials



Rahman A1*, Rahman AK1, Yamamoto T2 and Kitagawa H2
1Applied Research and Photonics, Friendship Road, Harrisburg, United States
2Graduate School of Science, Kyoto University, Kyoto-fu, Japan
*Corresponding Author:
Anis Rahman
Applied Research and Photonics, 470 Friendship Road, Suite 10
Harrisburg, PA 17111, United States
Tel: +1-717-623-8201
E-mail: a.rahman@arphotonics.net
http://www.omicsonline.org/open-access/terahertz-subnanometer-subsurface-imaging-of-2d-materials-2155-6210-1000221.php?aid=80210

Terahertz sub-surface imaging offers an effective solution for surface and 3D imaging because of minimal sample preparation requirements and its ability to “see” below the surface. Another important property is the ability to inspect on a layer-by layer basis via a non-contact route, non-destructive route. Terahertz 3D imager designed at Applied Research and Photonics (Harrisburg, PA) has been used to demonstrate reconstructive imaging with a resolution of less than a nanometer. Gridding with inverse distance to power equations has been described for 3D image formation. A continuous wave terahertz source derived from dendrimer dipole excitation has been used for reflection mode scanning in the three orthogonal directions. Both 2D and 3D images are generated for the analysis of silver iodide quantum dots’ size parameter. Layer by layer image analysis has been outlined. Graphical analysis was used for particle size and layer thickness determinations. The demonstrated results of quantum dot particle size checks well with those determined by TEM micrograph and powder X-ray diffraction analysis. The reported non-contact measurement system is expected to be useful for characterizing 2D and 3D naomaterials as well as for process development and/or quality inspection at the production line.




Friday, June 7, 2013

Abstract-Radially polarized terahertz waves from a photoconductive antenna with microstructures



K. Kan1, J. Yang1, A. Ogata1, S. Sakakihara1, T. Kondoh1, K. Norizawa1, I. Nozawa1, T. Toigawa1, Y. Yoshida1, H. Kitahara2, K. Takano2, M. Hangyo2, R. Kuroda3, and H. Toyokawa3
1Institute of Scientific and Industrial Research (ISIR), Osaka University, Osaka 567-0047, Japan
2Institute of Laser Engineering (ILE), Osaka University, Osaka 565-0871, Japan
3National Institute of Advanced Industrial Science and Technology (AIST), Ibaraki 305-8568, Japan                        

The generation of radially polarized terahertz (THz) waves from a photoconductive antenna (PCA) with radial microstructures was investigated. Microstructured electrodes with 10 μm lines and spaces were fabricated on a semi-insulating InP wafer using photolithography. The PCA with three layers was driven by an amplified femtosecond laser and DC power supply. Radially polarized THz waves from the PCA were measured by a Michelson interferometer with a 4.2 K silicon bolometer. The polarization components of THz waves were analyzed by a wire grid polarizer.
© 2013 AIP Publishing LLC