Hybrid modulation for short range polymer optical fiber communications

In order to effectively exploit the spectrum of step-index polymer optical fiber (SI-POF) transmission system, a hybrid modulation format based on discrete multi-tone modulation (DMT) and M-ray Pulse Position Shift Keying (MPPSK) is proposed. The sideband interference component of the novel modulation schemes is analyzed. A new numerical symbols generating approach is introduced to strengthen the anti-interference capability of the system. Offline processing with arbitrary waveform generator (AWG) and digital storage oscilloscope (DSO) is adopted to investigate the transmission performance. A transmission rate of 510.5Mbps is achieved for 50m SI-POF in intensity modulated direct detection system. The experimental verification demonstrates that with the help of the new methodology an additional bit rate of 19.5 Mbps at low signal-to-noise ratio (SNR) region is obtained. Furthermore 6dB power is saved at a BER of 1× 10^-4. Therefore, better spectrum efficiency can be achieved. The proposed modulation format combination can be also applied to other DMT and MPPSK over POF systems.