A broadband fiber transmission system includes a transmission line with at
least one zero dispersion wavelength .lambda..sub.o and transmits an
optical signal of .lambda.. The transmission line includes a distributed
Raman amplifier that amplifies the optical signal through Raman gain. One
or more semiconductor lasers are included and operated at wavelengths
.lambda..sub.p for generating a pump light to pump the Raman amplifier.
.lambda. is close to .lambda..sub.o and .lambda..sub.0 is less than 1540
nm or greater than 1560 nm.
