针对通信系统中CDMA光模块的非线性失真对整个系统性能的影响问题，本文从激光器和放大器两方面出发，通过采用三阶交调截点(IP3)和三阶交调产物(IM3)参数作为衡量CDMA光模块非线性失真的指标，详细地分析了光模块的失真特性，并在此基础上初步探讨了改善CDMA模块失真的基本方法，包括改变模块内部激光器的偏置电流，放大器的偏流及外围匹配电路在内的一系列方法。实验通过观察条件的改变对IP3和IM3的影响从而证实文中提出的方法行之有效，均能从一定程度上改善系统的失真指标。目前国内外对此类失真特性的研究一般集中在电性能上，对光器件与电器件相结合的研究涉及较少，本文提出的方法对实际商用化光模块产品有一定的借鉴意义，具有一定的使用价值。%Nonlinear distortion of CDMA optical module has severely affected the whole system performance in a communication system, for the problem, by the use of IP3(the third-order Intercept point) and IM3(third-order intermodulation signal) parameters as an index of measuring CDMA optical module nonlinear distortion, and distortion properties of optical modules is analyzed in detail from two aspects including lasers and amplifiers. On this basis, basic methods to improve the CDMA module distortion are discussed preliminarily, such a series of methods as changes to module internal laser bias currents, amplifier bias currents and peripheral matching circuits, and etc. The experimental results demonstrate that the proposed method is effective, which can improve the system distortion index in a certain degree, by watching influence on IP3 and IM3 parameters when condition changes. At present, the research for such distortion characteristics generally concentrated on the electrics, less on the optical devices combined with electrical devices at home and abroad. The method has certain significance and value for actual commercial optical module products.
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