线性调频激光器跳模抑制研究

发布时间：2018-11-04 09:16

【摘要】：近年来,合成孔径激光雷达凭借其能够打破衍射极限对于入瞳孔径的制约、改善传统激光雷达空间分辨能力的优势,在相干激光雷达探测体系中的地位愈发重要,其关键技术之一即为雷达探测光源宽带线性调频激光的获取。由于跳模现象在激光器频率调制过程中难以避免,因此,针对于线性调频激光器的跳模抑制研究工作就有着十分重要的意义。在理论部分,本文主要介绍了激光的模式理论和单纵模选取方法,对比各种选模方法的优缺点,最终确定本实验的单纵模选取方案为F-P标准具法,并对不同参数标准具的选模性能进行理论分析。本文针对于影响输出激光稳定性的各种因素及相应稳频手段也进行了简要阐述。分析了各种激光频率调制方法,选取直接腔长调制法作为实验方案。之后从增益损耗角度出发,介绍了导致均匀加宽激光器中跳模现象出现的本质原因为模式竞争效应,确定了改变标准具角度位置和谐振腔腔长来实现跳模抑制的实验方案。在实验部分,我们完成了所设计的跳模抑制系统的搭建,实现了基于Lab VIEW的跳模抑制系统控制程序开发,并从输出激光调频范围角度对于LD泵浦Nd:YVO4激光器进行相关的实验分析。从只改变标准具角度位置、只改变谐振腔腔长以及二者协调变化这三个方面进行实验研究。实验结果表明,标准具角度位置的改变主要影响其自由光谱区的移动,谐振腔腔长的改变主要影响腔内激光模式的移动,只有在二者协调变化时才能实现对于跳模的抑制。最终得到输出激光调频范围为4.40GHz,约为激光器谐振腔相邻纵模间隔长度的二倍,说明实验系统能有效地抑制跳模。
[Abstract]:In recent years, with its ability to break the restriction of diffraction limit on pupil diameter and improve the spatial resolution of traditional lidar, synthetic aperture lidar (SAR) plays an increasingly important role in coherent lidar detection system. One of its key technologies is the acquisition of broadband linear frequency modulation (LFM) laser of radar detection light source. Because the mode hopping phenomenon is difficult to avoid in the frequency modulation process of the laser, it is of great significance to study the mode hopping suppression of the LFM laser. In the theoretical part, this paper mainly introduces the laser mode theory and the single longitudinal mode selection method, compares the advantages and disadvantages of various modes selection methods, and finally determines that the single longitudinal mode selection scheme of this experiment is F-P standard method. The model selection performance of different parameter standard tools is analyzed theoretically. In this paper, the factors affecting the stability of the output laser and the corresponding frequency stabilization methods are also briefly described. Various laser frequency modulation methods are analyzed, and the direct cavity long modulation method is selected as the experimental scheme. Then from the angle of gain loss, the essential reason of mode hopping phenomenon in uniform broadening laser is the mode competition effect, and the experimental scheme of mode hopping suppression is determined by changing the standard angle position and cavity length. In the experiment part, we completed the design of the mode-hopping suppression system, and realized the control program development of the mode-hopping suppression system based on Lab VIEW. The experimental analysis of LD pumped Nd:YVO4 laser is carried out from the angle of the frequency modulation range of the output laser. The experimental study is carried out from only changing the angular position of the standard resonator, changing the cavity length and the coordination between the two. The experimental results show that the change of the standard angular position mainly affects the movement of the free spectral region, and the change of the cavity length mainly affects the laser mode movement in the cavity. Only when the two changes harmoniously can the mode hopping be suppressed. Finally, the frequency modulation range of the output laser is 4.40 GHz, which is about twice the length of the adjacent longitudinal mode interval in the laser resonator, which shows that the experimental system can effectively suppress the mode hopping.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN248

【参考文献】