中文摘要：

在模拟信号光纤通信系统中,链路的线性化程度和增益大小直接影响传输系统的性能,而这两种特性在很大程度上取决于链路中电信号调制和解调的方式.传统的传输方法是在发送端使用强度调制器对光信号进行强度调制,然后在接收端使用光电探测器实现电信号的解调.然而,由于传统方法中系统传递函数所固有的非线性效应,系统解调后的传输电信号质量会明显下降,产生信号失真,同时,系统的传输增益也较低,一般不超过-20dB.针对上述传统方法中的缺陷,提出一种基于负反馈解调机制的模拟信号光纤通信方法.该方法能够显著地减少电-光调制过程中所产生的非线性效应,同时提高了信号输出增益.经过一系列的数学推导,得到了关于该系统传输性能的解析表达式,并通过与数值仿真结果相比较,验证了该解析表达式的准确性和该传输系统的性能优越性.

英文摘要：

Analog fiber-optic communication system is a well-established technique that has been widely used in various applications.In these applications,the linearity and the link gain are the important figure of merits and directly determine the link＇s performance.It is well-known that these two characteristics are largely affected by the modulation and demodulation methods.In traditional systems,intensity modulation and direct detection are used to modulate and demodulate the signals.However,such methods suffer from two main inherent drawbacks：strong nonlinearity and low electrical conversion efficiency.As a result,the transmitted signal is highly distorted and the transmission link gain is normally less than-20 dB.In order to overcome these drawbacks,here we propose a fiber-optic communication method based on the intensity modulation and feedback demodulation techniques.In the communication link proposed by us,the transmitter is identical to that of the traditional system.However,at the receiver end,with the help of a balanced-detector,the received optical signal is intensity-mixed with a local optical signal to generate an error signal,which is proportional to the difference between the input and output signals of the fiber-optic analog link.By forming a feedback-loop and therefore forcing the error signal to be zero,the link＇s output signal becomes identical to the input signal and therefore various link＇s characteristics such as gain and linearity can be improved.We illustrate these improvements by first analytically deriving explicit expressions for the transmission function and the third-order distortion of the proposed link,and then validating them with the help of numerical simulations.To summarize,we have proposed an intensity-modulation and feedback-demodulation based fiber-optic analog link,which when compared with the traditional systems,can dramatically reduce the non-linear effects,and at the same time,significantly increase the output gain for analog fiber-optic transmissions.