OPTICAL TRANSMISSION METHOD AND APPARATUS USING OFDM

摘要

PROBLEM TO BE SOLVED: To achieve a higher spectral efficiency of OFDM sub-bands.SOLUTION: An optical add/drop multiplexer 1 splits a continuous waveband optical signal into an express path and a drop path. A band-pass filter 4 is provided in the drop path. The band-pass filter 4 has a filter bandwidth that covers the sub-band to be extracted. A band-stop filter 3 is provided in the express path to remove the sub-band to be extracted from the continuous waveband optical signal IN. An OFDM modulated optical add signal ADD can be added into the wavelength gap created through the band-stop filter 3. The sub-band carrying the optical add signal ADD occupies a wavelength range that is completely covered by the filter bandwidth of the band-stop filter 3. The difference between the filter bandwidths of the band-pass filter 4 and the band-stop filter 3 corresponds preferably to the slope of the filter edges of the filters 3 and 4.