从信号频域处理的角度分析并实验验证了一种基于微波光子滤波器的归零(RZ)码到非归零(NRZ)码的码型变换方案。理论上，通过对RZ和NRZ码基带信号的频谱特点以及微波光子滤波器的特性进行分析，构建一个低通滤波器并对RZ码信号进行滤波，强烈抑制RZ码信号中的时钟分量，最终实现RZ到NRZ码的码型转换。在实验中，采用一种两抽头加色散延时的微波光子滤波器对速率为10 Gbit/s的RZ码信号进行了处理，成功得到了转换后的NRZ码信号。信号波形和频谱均显示了此方案的良好性能。通过简单地调节微波光子滤波器的部分参数，可对任意速率的信号进行处理，具有很好的灵活性。

From the view of signal processing in the frequency domain, a scheme for the return-to-zero (RZ) to nonreturn-to-zero (NRZ) signal data format conversion based on a tunable microwave photonic filter is analyzed and demonstrated. Theoretically, the spectral characteristics of RZ and NRZ baseband signals and microwave photonic filter characteristics are analyzed. It is found that RZ to NRZ data format conversion can be successfully realized by a low-pass filter on the RZ signal with strong suppressing the clock component of the RZ data. In the experimental demonstration, a 10 Gbit/s NRZ signal is successfully converted from a RZ signal by utilizing an two-tap microwave photonic filter with two different light sources and intensity modulation. Both waveform and spectrum show the signal has good quality. In addition, signals with various repetition rate can be well processed by simply adjusting some parameters of the filter. It is shown that this scheme is very simple and flexible.