Nippon Telegraph and Telephone Corporation

Junichi Akahani

Masao Kawachi

Senichi Suzuki

Mitsuru Harada

Atsushi Takahara

Yuji Akatsu

Kazutosi Kato

Kennosuke Fukami

An optical wavelength division multiplexing transmission network system having a star-topology network is disclosed, which comprises an arrayed-waveguide grating type multiplexing/demultiplexing circuit having N input ports and N output ports, and N transmitting/receiving apparatuses, each apparatus including a transmitter, receiver, demultiplexer, multiplexer, and N 2-input and 2-output optical path switching elements corresponding to N wavelengths, so as to cope with a damage to a transmitting or receiving portion corresponding to a specific wavelength. Each switching element is independently switched between first and second connective conditions. In the first connective condition, the output port corresponding to a specific wavelength of the demultiplexer is connected to the input port corresponding to the specific wavelength of the receiver, and the output port corresponding to a specific wavelength of the transmitter is connected to the input port corresponding to the specific wavelength of the multiplexer; and in the second connective condition, the output port corresponding to a specific wavelength of the transmitter is connected to the input port corresponding to the specific wavelength of the receiver, and the output port corresponding to a specific wavelength of the demultiplexer is connected to the input port corresponding to the specific wavelength of the multiplexer.

Optical wavelength division multiplexing transmission network system using transmitting/receiving apparatuses having 2-input and 2-output optical path switching elements

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Nara, Japan

Junichi Akahani