Kazuki Kawai   Hikaru Takahashi   Tatsuya Omori   Ken Ya Hashimoto   
Japanese Journal of Applied Physics 61(SG) 2022年7月
This paper describes the implementation of an autofocus function for a laser beam in a high-speed, phase-sensitive laser probe system for RF surface/bulk acoustic wave devices. This implementation can compensate for defocus caused during continuou...
Toru Yaginuma   Tatsuya Omori   Ken Ya Hashimoto   
Japanese Journal of Applied Physics 60(SD) 2021年7月
This paper proposes a detection electronics which enables ultimate suppression of leakage signals in high-speed and phase-sensitive laser probe for radio frequency surface and bulk acoustic wave devices. Another merit is simpler circuit configurat...
Hikaru Takahashi   Tatsuya Omori   Ken Ya Hashimoto   
Japanese Journal of Applied Physics 60 2021年7月
This paper describes the coaxial integration of a Michelson interferometer (MI) and a Sagnac interferometer (SI) in a high-speed, phase-sensitive laser probe for surface acoustic wave/bulk acoustic wave devices. This combination enables the MI to ...
Naoto Matsuoka   Xinyi Li   Tatsuya Omori   Ken Ya Hashimoto   
Japanese Journal of Applied Physics 59(SK) 2020年7月
This paper discusses loss mechanisms of temperature compensated surface acoustic wave (TC-SAW) devices using the SiO2 overcoated 128°YX-LiNbO3 (128-LN) substrate. Analysis is based on the finite element method (FEM) combined with the hierarchical ...
Luyan Qiu   Xinyi Li   Naoto Matsuoka   Tatsuya Omori   Ken Ya Hashimoto   
Japanese Journal of Applied Physics 59(SK) 2020年7月
It is known that nonlinear responses by transverse resonances are more emphasized than those by the main resonance in radio frequency bulk acoustic wave devices. This paper investigates this mechanism using the LCR-based nonlinear equivalent circu...
Fumiaki Ukaji   Chang Jun Ahn   Tatsuya Omori   Ken Ya Hashimoto   
Proceedings of the IEEE International Conference on Industrial Technology 2016-May 860-865 2016年5月
Multi-user multi-input multi-output (MU-MIMO) can achieve more transmission speed and multi-user diversity. Furthermore, since frequency symbol spreading (FSS) can mitigate the effect of frequency selective fading, it is useful for improving the B...
Masaya Okamura   Chang Jun Ahn   Tatsuya Omori   Ken Ya Hashimoto   
2015 International Symposium on Intelligent Signal Processing and Communication Systems, ISPACS 2015 532-536 2016年3月
Massive MIMO has been recognized as promising ways to provide high speed data transmission. However, since the number of pilot symbol is proportionally depending on the number of transmit antenna, the total transmission rate of massive MIMO would ...
Kotaro Abe   Chang Jun Ahn   Tatsuya Omori   Ken Ya Hashimoto   
2015 International Symposium on Intelligent Signal Processing and Communication Systems, ISPACS 2015 417-421 2016年3月
Recently, visible light communication(VLC) is widely researched due to the spreading of LED usage. It satisfies demands of ubiquity and high speed communication. However, it is impossible to transmit the phase information and frequency information...