Optical transmission system and optical coupler/branching filter

Abstract

The objective is an optical transmission unit capable of coupling and branching signal lights of individual wavelengths at a data rate of 10 Gbits/s. In order to achieve the objective, DCFs are provided and proper values of dispersion compensation are given, so that different characteristics depending on the respective wavelengths to be coupled, split and pass through without being split are obtained. The signal lights are amplified by a plurality of low-excitation optical amplifiers to regain their light levels which are weakened due to using an optical coupler, branching filter and DCF together, thereby enabling a long-distance transmission.

1 - 6  (canceled).  
     
     
         7 : An optical transmission system comprising: 
 an optical transmission unit which receives signals of a plurality of wavelengths and multiplexes them together to transmit a desired signal;    a first dispersion compensating filter coupled to receive the desired signal and filter it to provide a filtered signal;    an optical unit coupled to receive the filtered signal and provide it to an optical branching filter which selects a first wavelength signal from the filtered signal and provides the filtered signal to an optical coupler which adds a second wavelength signal to the filtered signal to thereby create a further signal and provides the further signal to a second dispersion compensating filter for transmission to a receiving station.