US Patent 7539417 Optical transmission system

The invention relates to an optical transmission system which allows high quality transmission of signal light, and has a configuration that is suitable particularly for CWDM optical transmission. In the optical transmission system, signal channels outputted from non-temperature controlled direct modulation light sources are multiplexed by a multiplexer, transmitted through an optical fiber transmission line, and demultiplexed into a first wavelength band Λ1 and second wavelength band Λ2 by a demultiplexer. The signal channel group in the second wavelength band Λ2 of which the absolute value of chromatic dispersion is large is dispersion-compensated for by a non-temperature controlled dispersion compensator. The chromatic dispersion of the signal channels in the second wavelength band Λ2 after passing through the dispersion compensator is set to be negative over a temperature range of 0° C. to 60° C.