Experimental demonstration of an optimized 16-ary four-dimensional modulation format using optical OFDM

We experimentally demonstrate the best known 16-ary 4-d modulation format at 24.8 Gb/s using coherent optical OFDM, achieving 0.58 dB OSNR gain over PDM-QPSK at a SER of 10
^-2
. With 7% overhead optimal codes, a 0.38 dB gain is theoretically achievable.