直接检测式光接收机中的噪声分析

提出了基于窄带高斯过程的光接收机模型，改进了基于Karhunen-Loève变换的光接收机模型以包含波分复用（WDM）系统中的主要传输损伤. 得到了2种模型各自条件下判决电流的统计特征，并证明了2种方法在一定程度上是一致的. 所得解析结果与Monte-Carlo仿真结果精确吻合，可用于误码率的精确计算. 通过比较，说明高斯近似法估算的误码率过大，故其应用范围受到限制. 改进的Karhunen-Loève变换法具有很强的可扩展性，通过推广可以包含更多的因素，因此该方法可以作为IM-DD光传输系统性能精确评估的通用方法.

Noise Analysis for Direct Detection Optical Receivers

An optical receiver model based on narrowband Guassion process was proposed. Moreover, the receiver model based on Karhunen-Loève transform was improved to include the main transmission impairments in wavelength division multiplexing system. The statistics of the decision current in two models were obtained and turned out to be consistent in some degree. The two analytical results show exact agreement with that of Monte-Carlo simulations, so they are reliable for accurate estimation of bit error ratio (BER). By comparison with the analytical results, Gaussion approximation method tends to overestimate the BER whose application is restricted within narrow limits. The improved Karhunen-Loève transform approach is of great scalability, with which more factors can be taken into account through proper modification, so it can serve as a general method for performance evaluation of IM-DD optical transmission systems.