LAUSR

In this paper, a delta–sigma modulation is proposed for the orthogonal frequency division multiplexed-passive optical network (OFDM-PON) to enable transmission of OFDM signals via binary intensity modulation and direct detection (IM-DD) channels. The delta–sigma modulation is an independent digital signal processing block that converts the analog OFDM signal into binary bit sequence. The OFDM signal can be simply retrieved from the bit sequence, using a low-pass filter at the receiver. Neither the analog-to-digital converter (ADC)/digital-to-analog converter (DAC) nor the linear modulator/detector are required, which means the proposed system can be fulfilled by employing cost-effective 10- or 40-Gb/s binary optics and electronics. Besides, the delta–sigma-modulated OFDM-PON is able to offer excellent robustness against noises and nonlinear distortions. In the experimental demonstration, the performance of proposed delta–sigma-modulated OFDM-PON system has been investigated. It is found that around a 4-dB improvement in receiver sensitivity is achieved, compared to a traditional analog OFDM-PON scheme.