Software defined transceivers for high-speed flexible optical networks

A novel high-capacity, energy-efficient and bit-rate flexible optical transceiver (Tx/Rx), capable of supporting rates from 10Gb/s to beyond 1Tb/s, has been designed and its performance in long-haul transmission has been carefully investigated. The device can realize both orthogonal frequency division multiplexing (OFDM) and Nyquist wavelength division multiplexing (NWDM), for flexible super-channel generation; the inverse discrete Fourier transform (IDFT) and the discrete Fourier transform (DFT) are implemented directly in the optical domain, using a specially designed arrayed waveguide grating (AWG). Therefore, the transceiver can provide ultra-high capacity with significant improvements on the energy efficiency per transmitted bit. In addition, different modulation formats are possible, and different bit rates. In the present paper, we provide complete design guidelines of the AWG-based device that performs the IDFT/DFT, evaluating the influence of the slab diffraction effect on the orthogonality of the subchannels. The complete functionality of the transceiver is numerically simulated and the influence of the noise from the inline amplifiers, chromatic dispersion, non-linear effects have been evaluated. In addition, to simplify the receiver architecture, a pulsed local oscillator is used for coherent balanced photodetection, and the impairments due to the phase noise have been investigated. The system performance is evaluated considering both bit error rate (BER) and the error vector magnitude (EVM) parameters.