Patents by Inventor Kenji Tomooka

Kenji Tomooka has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Optical fiber transmission system and supervision method of the same
    Patent number: 5500756
    Abstract: An optical repeater for realizing transmission of supervisory information of an optical fiber transmission system without the output power of an optical fiber amplifier being reduced, wherein a supervisory optical transmitter and optical receiver with a wavelength which is similar to the wavelength of the pumping light source of the optical fiber amplifier are mounted, and on the input side of the optical repeater, pumping light is multiplexed in the forward direction and a supervisory optical signal, which is multiplexed in wavelength and transmitted, is demultiplexed simultaneously by the first wavelength multi- and demultiplexer and they are received by the supervisory optical receiver, and on the output side of the optical repeater, pumping light is muitiplexed in the reverse direction and a supervisory optical signal outputted from the supervisory optical transmitter is multiplexed by the second wavelength multi- and demultiplexer.
    Type: Grant
    Filed: February 26, 1993
    Date of Patent: March 19, 1996
    Assignee: Hitachi, Ltd.
    Inventors: Hideaki Tsushima, Shinya Sasaki, Yukio Nakano, Hiroyuki Nakano, Ryoji Tateyari, Hironari Matsuda, Kenji Tomooka, Naohiro Sakakida, Shin Nishimura, Yoshihiro Yano, Youichi Igarashi, Satoshi Aoki, Masahiro Takatori, Tohru Kazawa, Yoshihiro Ashi