高峰均比是 OFDM通信系统的主要缺点之一，光 OFDM通信系统也存在同样的问题。本文将联合 Hadamard变换和限幅 (Clipping)方法抑制峰均功率比算法成功应用到直接检测的光正交频分复用光纤传输实验平台，重点研究了算法对系统误码性能的影响。实验中产生的 2.5 Gb/s QPSK OFDM光信号在标准单模光纤中传输 100 km。实验结果表明：与原始的光传输通信系统相比，采用所提出的联合抑制 OFDM信号峰均比算法能减下 PAPR 3.2 dB，同时系统中接收机灵敏度提高 3 dB左右。

The high peak-to-average power ratio is the main disadvantage of Orthogonal Frequency-division Multiplexing (OFDM) communication systems, so there is the same problem in optical OFDM systems. A joint reduction Peak-to-average Power Ratio (PAPR) scheme, based on combining Hadamard transform with clipping, is successfully applied to an experimental system of direct-detection optical OFDM signal transmission over fiber. The performance of bit error rate of system is mainly researched. In this experiment, the 2.5 Gb/s QPSK optical OFDM signal with Hadamard transformation is generated and transmitted over single mode fiber. The experiment results show that the proposed scheme can reduce PAPR almost 3.2 dB. Meantime, the received sensitivity is improved 3dB with 100 km fiber transmission compared to that of ordinary optical direct detection OFDM system.