| 摘要 |
The invention provides a dispersion shift optical fiber which is capable of a zero dispersion wavelength division multiplex optical transmission in the wavelength band of 1550 nm and a wavelength division multiplex transmission using the optical fiber. With the dispersion shift optical fiber according to the invention, the relationship between the relative refractive index difference DELTA -1 of a core of an optical fiber, the relative refractive index difference DELTA -2 of the first clad covering the core, and the relative refractive index difference DELTA 3 of the second clad covering the outer circumferential side thereof is DELTA 1> DELTA 3> DELTA 2, the mean dispersion slope of the use wavelength band of a wavelength from 1530 nm to 1560 nm is made a negative value, and the zero dispersion wavelength is set to a value which is outside the gain band of an erbium-doped fiber amplifier. A wavelength division multiplex transmission system according to the invention is constructed by connecting the above-mentioned dispersion shift optical fiber to a positive dispersion slope optical fiber which has a positive dispersion slope in the wavelength range from 1530 nm to 1560 nm and has almost the same zero dispersion wavelength, whereby the dispersion slope of the positive dispersion slope optical fiber is counterbalanced and compensated and the dispersion around a wavelength from 1530 nm to 1560 nm is made almost zero.
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