Radio frequency/microwave-directed energy sources using wide bandgap SiC photoconductive semiconductors have attracted much attention due to their unique advantages of high-power output and multi-parameter adjustable ability. Over the past several years, benefitting from the sustainable innovations in laser technology and the significant progress in materials technology, megawatt-class output power electrical pulses with a flexible frequency in the P and L microwave wavebands have been achieved by photoconductive semiconductor devices. Here, we mainly summarize and review the recent progress of the high-power photonic microwave generation based on the SiC photoconductive semiconductor devices in the linear modulation mode, including the mechanism, system architecture, critical technology, and experimental demonstration of the proposed high-power photonic microwave sources. The outlooks and challenges for the future of multi-channel power synthesis development of higher power photonic microwave using wide bandgap photoconductors are also discussed.

低相位噪声微波信号在通信、雷达、时频计量、深空探测等领域中不可或缺，光子学微波信号产生近年来发展快速，有望在载波频率、调谐性、相噪、可集成、功耗等多个方面突破传统电子学微波信号产生瓶颈。早期的光生微波系统复杂，激光器以及相关稳定设备体积庞大，难以在实验室以外的场所应用。近年来，基于微谐振腔的光学频率梳的迅速发展，凭借其低损耗、小体积、强稳定的优势，基于微腔光梳的微波光子学应用吸引了研究者们的广泛关注，其中基于微腔光梳的光生微波系统得到深入研究。文中将综述国内外近10年来基于微腔光梳的低相噪微波信号产生发展状况，并对基于微腔光梳的光生微波系统在未来应用中的主要挑战与发展趋势作以展望。

We demonstrate an all-fiber-based photonic microwave generation with 10-15 frequency instability. The system consists of an ultra-stable laser by optical fiber delay line, an all-fiber-based “figure-of-nine” optical frequency comb, a high signal-to-noise ratio photonic detection unit, and a microwave frequency synthesizer. The whole optical links are made from optical fiber and optical fiber components, which renders the whole system compactness, reliability, and robustness with respect to environmental influences. Frequency instabilities of 3.5×10-15 at 100 s for 6.834 GHz signal and 4.3×10-15 at 100 s for 9.192 GHz signal were achieved.

微波信号检测是电子信息领域的关键技术，广泛应用于通信、雷达、电子战。随着新一代信息技术的快速发展，现有的微波测量系统面临着速率和带宽瓶颈。微波光子学技术融合了微波和光波技术各自优势，具有大带宽、低损耗、抗电磁干扰等优势，文中围绕微波光子检测，特别是微波光子信号的频率测量方案，如频率-幅度映射型、频率-时间映射型、光信道化型等，介绍与分析国内外现状与发展动态，并对现有微波光子测量面临的问题和下一步发展方向进行了简单总结。

提出一种倍频因子连续可调，且相位连续变化的微波光子移相系统.系统主要由两个集成双偏振双平行马赫增德尔调制器组成，在不使用光滤波器的情况下，调节双平行马赫曾德尔调制器及相位调制器的射频驱动和直流偏置电压，生成二倍频，三倍频，…，六倍频微波信号，同时实现输出微波信号相位0~360°连续可调.仿真结果表明，当射频信号频率为10 GHz时，可分别产生频率为20、30、40、50、60 GHz的微波信号.调节相位调制器的直流偏置电压与半波电压比值从-1到1变化时，对应微波信号的相位从-180°到180°变化.此外，分析了调制器消光比对输出微波信号光载波抑制比和电杂散抑制比的影响，以及90°电桥相位平衡对微波信号相位漂移和幅度波动的影响.