Nippon Telegraph and Telephone Corporation

Ryu-ichi Watanabe

Kiyomi Kumozaki

Norio Tamaki

Masashi Hashomoto

An optical WDM transmission system formed by integrating by using an optical WDM device at least two point-to-multipoint optical transmission systems which provide independent services by using optical signals of different wavelengths. It provides a plurality of user terminals with optical signals obtained by splitting with an optical splitter an optical signal which is wavelength multiplexed by the WDM device. The splitting numbers of optical splitters placed ahead of or behind the WDM device are set such that a loss from the center terminal to the user terminals of each optical transmission system falls within an allowed loss of each system. Since the splitting numbers of the optical system of each system can be set independently, each system can accommodate a maximum number of user terminals per center terminal within the allowed loss of the system.

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Zushi, Japan

Ryu-ichi Watanabe