微波光纤链路相对于传统微波链路具有大带宽，低损耗等特点，它是微波光子学的基础单元，并被广泛应用于雷达、电子战等领域。作为其光源的半导体激光器，降低其相对强度噪声(RIN)可显著提高链路的无杂散动态范围，同时降低链路的噪声系数。为适应未来基于微波光纤链路的通信需求，人们对半导体激光器的RIN噪声提出了更高要求，因此有必要寻找新的思路以突破目前已有降低RIN噪声技术方案的瓶颈。论文提出了采用相干阵列激光器合成的新思路，通过降低相干光源噪声相关性以降低光源RIN噪声，使其单元激光器之间波长相干而噪声不相关，具体采用单向注入锁定阵列技术。 为研究单向注入锁定阵列激光器的RIN噪声特性，论文首先以近单模半导体激光器为研究对象，全面分析了其噪声来源和RIN噪声机理，并在此基础上研究了未激射模式对近单模激光器RIN噪声的影响，阐述了DFB激光器相比于FP激光器在降低RIN噪声方面的优势。 接着通过理论建模对单向注入锁定激光器阵列的RIN噪声特性进行研究，发现单向注入锁定阵列技术可使得激光器阵列的RIN噪声降低为单个激光器的1/N（N为阵列中激光器数量）。在研究过程中论文提出了更可靠的稳定锁定区确定方法，研究了阵列的相位稳定性并提出了阵列相位稳定性测试方法，详细研究了单向注入锁定阵列RIN噪声机理，并分析了锁定参数与合束参数对阵列RIN噪声的影响。 之后，本论文对单向注入锁定阵列降低RIN噪声方案采用分立器件与集成器件进行了实验验证。利用两个单元的激光器阵列实现了3 dB的RIN噪声降低，验证了该技术方案的正确性。研究发现集成器件可以克服分立器件合束相位不稳定的问题并显著减小合束延时差。论文在解决集成器件的一些设计与制作问题后，实现了低RIN噪声的集成单向注入锁定阵列的稳定工作。 最后，本论文对互注入锁定半导体激光器的RIN噪声进行了理论和实验研究，发现弱耦合互注入锁定对降低RIN噪声没有明显效果，因此在单向注入锁定激光器阵列中须用隔离器抑制主、从激光器之间的弱反馈干扰。在研究弱耦合互注入锁定RIN噪声特性时，论文还提出了基于噪声相关性的迭代分析方法，此方法可避免传统数值求解的诸多问题，能够更简洁、精确地得到其RIN噪声特性。

Compared with the traditional microwave links, microwave fiber-optic links have the characteristics of large bandwidth and low loss, which is the basic unit of microwave photonics. Microwave fiber-optic links are widely used in many fields, such as radar and electronic warfare. Semiconductor lasers with low RIN can improve the SFDR and reduce the NF of the links significantly. To meet the demand of future communication based on microwave fiber-optic links, lower RIN of semiconductor lasers is required. Therefore, it is necessary to find new methods to break through the bottleneck of existing technical solutions. In this paper, a new method is proposed by combining coherent lasers array. The idea reduces the correlation of noise in the semiconductor lasers array and makes the array coherent while the noise uncorrelated. To realize the idea, the technology of unidirectional injection locking laser array is adopted. To investigate the RIN of laser array under unidirectional injection locking, the nearly single-mode semiconductor laser is studied firstly. The noise sources are summarized, and the RIN mechanism are analyzed. The effect of the unoscillated mode on the RIN of nearly single-mode semiconductor laser is analyzed based on the results above. It is found that the RIN characteristics of DFB lasers is superior to Fabry-Perot (FP) laser. The RIN characteristics of the array under unidirectional injection locking is investigated based on our theoretical model. It is found that the RIN of the laser array could be reduced to 1/N of a single laser (N is the number of lasers in the array). In the process of research, a more reliable method to determine the stable locking region is proposed. The phase stability of the array is studied and a method to test the phase stability of the array is proposed as well. The RIN mechanism of the array under unidirectional injection locking is studied in detail, and the effect of the injection locking parameters and combining parameters on the RIN of the array is analyzed as well. The RIN of the unidirectional injection locking array was experimentally verified by discrete and integrated devices. A 3 dB RIN reduction is obtained by the array with two cells, which proves the correctness of the technology. It is found that the integrated device can overcome the instability fo the combining phase and reduce the combining delay difference significantly. Some key design and fabrication issues of integrated devices are solved, then the lasers array under unidirectional injection locking operates stably with low RIN characteristics. At last, the RIN of mutual injection locked semiconductor laser is investigated. It is found that the mutual injection locking with weak coupling strength has almost no effect on RIN. The result implies the necessity of isolator in the integrated device to avoid the weak disturbance between the master and the slave lasers. A new method based on noise correlation analysis is proposed as well. It can avoid many problems of the traditional numerical method, and obtain the RIN accurarely and compactly.