Patent ID: 7127168

Claim:
A multi-wavelength optical modulation circuit, comprising: a wavelength-group demultiplexer that receives multi-wavelength light having a plurality of wavelengths and demultiplexes the multi-wavelength light into wavelength groups formed from the respective plurality of wavelengths; a plurality of channel demultiplexers that demultiplex each wavelength group into light of the respective wavelengths; a plurality of optical modulators that modulates the light of respective wavelengths demultiplexed by the channel demultiplexers with transmission signals; a plurality of channel multiplexers that multiplex the modulated signal light of each wavelength output from the optical modulators for each wavelength group; and a wavelength-group multiplexer that multiplexes the wavelength-division multiplexed signal light of each wavelength group output from each channel multiplexer, wherein a frequency band of the multi-wavelength light is equal to or greater than free spectral ranges of the channel demultiplexers and the channel multiplexers, the wavelength-group demultiplexer and the wavelength-group multiplexer have free spectral ranges equal to or greater than the frequency band of the multi-wavelength light, and the channel demultiplexers and the channel multiplexers have free spectral ranges that correspond to a difference in transmission center frequencies between ports of the wavelength-group demultiplexer and the wavelength-group multiplexer where wavelengths are adjacent.