A signal processing apparatus, being configured for transmitting and receiving coherent parallel optical signals, comprises a transmitter apparatus including a first single soliton micro-resonator device and a modulator device, wherein the first single soliton micro-resonator device is adapted for creating a single soliton providing a first frequency comb, wherein the first frequency comb provides a plurality of equidistant optical carriers with a frequency spacing corresponding to a free spectral range of the first single soliton micro-resonator device, and the modulator device is adapted for modulating the optical carriers according to data to be transmitted, and a receiver apparatus including a coherent receiver device with a plurality of coherent receivers and a local oscillator device providing a plurality of reference optical signals, wherein the coherent receiver device and the local oscillator device are arranged for coherently detecting the transmitted modulated optical carriers, wherein the signal processing apparatus further includes at least one second single soliton micro-resonator device having a free spectral range being equal or approximated to the free spectral range of the first single soliton micro-resonator device and being adapted for creating at least one single soliton providing at least one second frequency comb, wherein the at least one second frequency comb provides at least one of additional optical carriers and the reference optical signals. Furthermore, a signal processing method, including transmitting and receiving coherent parallel optical signals via a communication channel is described.