高功率光载微波脉冲的产生及其大气中相位噪声特性的研究

光载微波（optically carried microwave signal）是近年来出现在光电子学领域的一个新概念，其实质是光波上加载了频率在微波波段的信号。由于光载微波兼具光波的传输特性及微波的频域特性，在计量学，非线性光学，太赫兹光学，光谱学，高分辨率雷达等领域有着广泛的潜在应用。本申请提出应用激光方法产生高功率光载微波脉冲信号，拟在半导体激光泵浦单块非平面环形腔及耦合腔固体激光器两种结构中，分别引入双折射机制实现同源相干双频激光振荡，利用半导体泵浦光纤功率放大器对脉冲双频激光信号进行功率放大，连续运转下得到不小于10瓦的光载微波信号。采用被动调Q机制实现双频脉冲激光输出，脉冲峰值功率10千瓦以上。定量研究光载微波信号的相位噪声特性和抗大气干扰能力，旨在为光载微波这一交叉学科的新概念在高分辨率成像探测及遥感系统中的应用打好技术基础。

Rf/microwave photonic technologies have received intense interest due to their applications in high resolution lidar, wireless communications, terahertz generation，and metrology. Nevertheless, most of the efforts are put to generate low power rf/microwave optical signal with large frequency difference, power scaling of rf/microwave signal has not received enough attentions. However, high power rf/microwave optical signals are needed for many applications such as lidar, remote sensing and long-range transmission of rf high-purity references in free space optical communications. Moreover, the knowledge of phase noise features of an optical carried rf/microwave signal in atmosphere is also essential for such applications. .We propose to study and develop dual-frequency pulsed lasers and fiber power amplifiers as well as investigate the phase noise features of the optically carried rf/microwave signals. The objectives of this project are to achieve high power optically carried microwave signal up to ten watts in CW mode and 10 KW peak power in pulsed mode. In addition, theoretical modeling and quantitative descriptions about the phase noise of an optically carried microwave signal in atmosphere will also be studied..We propose to implement the dual frequency laser with two approaches, the first approach is a dual-frequency laser setup with coupled cavity design. An adjustable linear phase anisotropy device is inserted to lift the degeneracy of the two orthogonal linear eigenstates to generate two-frequency signal. By this method the frequency of the microwave signal can be tuned continuously. The second approach is to glue an anisotropy crystal to a monolithic non planar ring oscillator to obtain two-frequency output. A passive Q-switch will be implemented to generate two-frequency laser pulses. The output from the dual frequency oscillator will be amplified by diode laser pumped fiber power amplifiers to scale up the power of dual frequency signal. A theoretical modeling of phase noise and the degradation of coherence of optically carried rf/microwave signal undergoing turbulent atmosphere will be developed. An atmospheric turbulence generator will be built to study the degradation of coherence of optically carried microwave signal when it passes through an atmospheric turbulence.