Liu Xinkai, Pan Wei, Zou Xihua, Yan Lianshan, Luo Bin, Zheng Di, Ye Jia, Lu Bing
Opt Express. 2016 Aug 22;24(17):19592-9. doi: 10.1364/OE.24.019592.
A photonic approach for generating chirped microwave pulses with a flexible and fine parameter manipulation is proposed and experimentally demonstrated. In the proposed system, an intensity modulator (IM) biased at the minimum transmission point is used to generate two ± 1st-order optical sidebands which are then sent to a phase modulator (PM) for implementing large-signal phase modulations. A de-interleaver combined with an optical variable delay line (OVDL) is utilized to introduce a time delay between two phase-modulated optical signals. A second IM that acts as a time domain intensity switch (TDIS) is used to select different phase modulation ranges of the two phase-modulated optical signals. After the optical-electrical conversion in a photodetector (PD), chirped microwave pulses are generated. The key feature of this approach is that the parameters of the generated chirped microwave pulses including central frequency, pulse repetition frequency, and chirp rate can be flexibly and precisely manipulated by the radio frequency (RF) signals applied to modulators. A proof-of-principle experiment is carried out to verify the proposed approach. Consequently, positive or negative chirped microwave pulses with different central frequencies at 20, 22, 24 or 26 GHz and different pulse repetition frequencies at 1.5 or 2 GHz are generated, respectively.
提出并通过实验证明了一种用于生成具有灵活且精细参数操控的啁啾微波脉冲的光子学方法。在所提出的系统中，一个偏置在最小传输点的强度调制器（IM）用于生成两个±1阶光学边带，然后将它们发送到一个相位调制器（PM）以实现大信号相位调制。一个与光学可变延迟线（OVDL）相结合的解复用器用于在两个相位调制光信号之间引入时间延迟。第二个用作时域强度开关（TDIS）的IM用于选择两个相位调制光信号的不同相位调制范围。在光电探测器（PD）中进行光电转换后，生成啁啾微波脉冲。该方法的关键特性在于，所生成的啁啾微波脉冲的参数，包括中心频率、脉冲重复频率和啁啾率，可以通过施加到调制器的射频（RF）信号进行灵活且精确的操控。开展了原理验证实验以验证所提出的方法。结果分别生成了中心频率为20、22、24或26 GHz且脉冲重复频率为1.5或2 GHz的不同的正啁啾或负啁啾微波脉冲。
