Nippon Telegraph and Telephone Corporation

Seiji Norimatsu

Jun-ichi Kani

Shigeki Aisawa

Tadashi Sakamoto

Masahiko Jinno

Kazushige Yonenaga

Shigeru Kuwano

Nori Shibata

In a wavelength division multiplexed optical transmission system wherein the zero dispersion wavelength of the optical fiber transmission pathis in the 1550 nm region, among multiplexed optical signals, the wavelengths of either of at least two optical signals are allocated between 1450 nm and 1530 nm, or between 1570 nm and 1650 nm.

Wavelength division multiplex optical transmission system

In a wavelength division multiplexed optical transmission system wherein the zero dispersion wavelength of the optical fiber transmission path is in the 1550 nm region, among multiplexed optical signals, the wavelengths of either of at least two optical signals are allocated between 1450 nm and 1530 nm, or between 1570 mn and 1650 nm.

Wavelength division multiplexing optical transmission system

In a transmitter side in an optical transmission system, an input binary signal is converted into a duobinary signal, and the duobinary signal is applied to an optical modulation device which provides an optical intensity modulation signal, wherein the optical intensity for a center value of the duobinary signal is a minimum, the optical intensity for the other two values of the duobinary signal is a maximum, and an optical phase for those two values is opposite to each other. In a receiver side, simple direct detection is carried out for receiving optical signal through an optical transmission line to provide a demodulated binary signal. Thus, an original binary signal is recovered without a duobinary decoder and receiver sensitivity degradation. In the optical transmission system, an optical carrier frequency component in a signal spectrum is suppressed, a signal bandwidth of the modulated light is reduced in half to that of a prior art, so an optical transmission system for long distance, high bit rate and large traffic capacity is obtained.

Optical transmission system

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Tokyo, Japan

Seiji Norimatsu