峰均功率比(PAPR)问题是OFDM系统的主要缺陷之一， 在光OFDM系统中，由于调制器、D/A转换器、功率放大器和光纤的非线性，高峰均功率比的信号将会产生严重畸变，对系统的性能造成较大的影响。介绍了降低OFDM系统PAPR的主要方法，包括信号预畸变技术、编码技术和概率类技术，并对星座图扩展(ACE)方法和脉冲成形(PS)方法进行了仿真分析，讨论了各自的优缺点及改进的空间。

In optical OFDM system, because of the nonlinearity of the modulator, D/A conversion devices, power amplifiers and optical fiber, the signals with a high peaktoaverage power ratio (PAPR) will greatly reduce the efficiency of the system. In this paper, the main methods for reducing PAPR are introduced, including predistortion technology, coding technology and probability technology. Simulations on constellation extension (CE) and pulse shaping (PS) methods are presented by Matlab, and their virtues, shortcomings and improvements are analyzed.