| 摘要 |
PROBLEM TO BE SOLVED: To perform excellent wavelength multiplex transmission without generating a large attenuation rate by using a low gradient mono mode fiber which is a dispersion flat fiber provided with two wavelength dispersion zeros on the outside of the band of the multiplex of a wavelength. SOLUTION: A fiber for a low gradient type cable is used and dispersion accumulated on the fiber for the cable is corrected by a step index type fiber. For the low gradient fiber, the fiber provided with wavelength dispersion for taking an absolute value between 3-5 ps/nm.km within the band of a multiplex channel is used. The band of the multiplex channel correspond to the wavelength between 1530-1600 nm and the wavelength dispersion inside the fiber becomes sufficiently large in terms of nonlinear action, especially 4-wave mixing limit by the lower limit of the dispersion. Also, by an upper limit, just by using the step index type fiber, the wavelength dispersion on a link is corrected. Such a wavelength dispersion value is obtained by the dispersion flat fiber for which the dispersion between zeros indicates parabola characteristics and a vertex corresponds to the positive or negative value of the wavelength dispersion. |
