Integrated wavelength conversion for adaptively modulated WDM-OFDM signals in a silicon waveguide

All-optical wavelength conversion for 2×11.64 GBaud adaptively-modulated orthogonal frequency division multiplexing (AM-OFDM) signals with QPSK/16QAM formats is experimentally demonstrated in a silicon waveguide. The AM-OFDM signal with partly higher- (and lower-) order formats on lower- (and higher-) frequency subcarriers has better overall conversion performance in receiving optical signal-to-noise ratio and power penalty. In comparison with the OFDM-QPSK signal, at the BER of 3.8×10^-3, the bit rate increases 11.64 Gbit/s per channel almost without conversion power penalty increased by replacing the QPSK sequence with the 16QAM sequence on half subcarriers.