The direct-detection optical orthogonal frequency division multiplexing(O-OFDM) system with companding transform(CT) technique is investigated by simulation and experiment to reduce the peak-to-average power ratio(PAPR) of OFDM signals and improve the sensitivity of the receiver.The simulation results show that when increasing the companding coefficient μ,the PAPR of the OFDM signal decreases and the bit error rate(BER) of the system firstly decreases and then increases.We can choose a proper μ ...