Vector 8QAM signal generation and transmission based on optical carrier suppression

We experimentally demonstrate how to generate photonic eight quadrature amplitude modulation (M-QAM) vector signal by using only one Mach-Zehnder modulator (MZM). Because of the 'square-law' characteristic of the photodetector (PD), the amplitudes and the phase of the driving radio-frequency (RF) signal are changed after detection. The pre-coding for the amplitudes and the phase of the driving radio-frequency (RF) signal before they drive the MZM will take the advantages of restoring the driving precoding signal to regular signal after PD. The transmission performance with different date rates at 1, 2, and 3-Gbaud over single-mode fiber (SMF) transmission is experimentally demonstrated. The bit-error ratios (BERs) of the transmission system are less than the forward-error-correction (FEC) threshold of 3.8×10−3.