Guard-band influence on orthogonal-band-multiplexed coherent optical OFDM

Coherent optical orthogonal frequency-division multiplexing (OFDM) has recently been demonstrated beyond 100 Gb/s using orthogonal band multiplexing (OBM). OBM-OFDM gives a multitude of benefits in implementing high-speed optical OFDM transmission. We investigate the system sensitivity to the guard band of OBM-OFDM. The result suggests that when the guard band equals a multiple of the subcarrier spacing, the Q penalty practically vanishes. We also show that two OFDM bands can be demodulated simultaneously with one fast Fourier transform, owing to interband orthogonality, and its performance is almost the same as one-band detection.