【作者】 崔柳；

【导师】 张书练；

【作者基本信息】 清华大学 ， 光学工程， 2009， 博士

【摘要】 正交偏振双频激光回馈现象蕴含丰富的激光物理内容。将其用于位移测量是应用推广的基本技术。且回馈位移测量系统具有成本低、精度高等优点。但目前缺乏系统有效的理论来解释正交偏振双频激光回馈的物理机制,回馈位移测量系统也还未考虑稳频来保证测量精度。本文系统的研究了正交偏振双频氦氖激光器光回馈现象的机理,提出了在光回馈存在的情况下稳定激光器频率的方法,并研制了稳频的回馈位移测量系统。论文主要内容与研究成果有:（1）建立基于腔调谐的正交偏振光回馈理论模型,该模型在Lamb半经典气体激光器理论基础上,考虑矢量化和双频输出的扩展;利用三腔镜F-P腔的分析方法,将激光回馈效应耦合到谐振腔内研究;采用多光束干涉的叠加方法处理不同回馈水平。模型解释了频率分裂氦氖激光回馈中发现的光强分叉和等光强点处的“驼背”新现象。（2）理论和实验研究了激光回馈效应对激光器增益特性的影响,发现:回馈光对激光谐振腔的调制导致①净增益曲线在无光回馈的高斯型增益曲线基础上叠加周期性的尖峰,该尖峰的带宽由外腔和内腔长的比例决定;②净增益曲线被展宽,氦氖激光器出光带宽变大;③净增益系数值增大,光强调制深度变大。这些是产生频率分裂氦氖激光回馈新现象的物理机制。（3）研究了影响回馈条纹形态的主要因素,发现回馈条纹的幅值随回馈镜反射率的增大而增大,对同一反射率,回馈腔长越长,幅值越大;回馈条纹的相位延迟量由两正交偏振频率间的频差和回馈腔长共同决定,理论分析与实验结果吻合。（4）提出峰值检测和均值比较两种动态稳频的方案,并与静态等光强点稳频方法相结合,给出了回馈位移测量系统的稳频方案,使系统在大范围和非实验室环境下可稳定快速准确的工作。该研究具有实用意义。（5）基于以上研究成果,研制成稳频的回馈位移测量系统,并与Aglient5529A双频激光干涉仪进行了比对。系统指标为:量程100mm,最小测量单位79.106291nm,测量速度范围36μm/s～3cm/s,全程测量标准差小于0.4μm,线性度误差7×10^-6左右,动态频率稳定度优于10?7。该系统抗干扰能力强、结构简单、使用方便、非接触式测量,具有良好的应用前景。更多还原

【Abstract】 The optical feedback effects in orthogonal polarized lasers contain plenty of knowledge of laser physics. Their applications in displacement measurement are the basic technology of metrology field and have the advantage of low cost and high accuracy. However, there is lack of systemic and effective theories to explain the physical principle behind the novel phenomena of optical feedback effects in orthogonal polarized lasers. The frequency stabilization of displacement measuring system is not considered to ensure the measurement accuracy. In this dissertation, the principle on optical feedback effects in orthogonal polarized lasers is systematically studied, the method of stabilized lasers’output frequency when optical feedback effect exists is proposed, and a set of displacement measuring system is developed.Main research contents and achievements include: （1） An orthogonal polarized laser feedback theory model based on cavity tuning is created. Lamb’s semi-classical theory’s vectorial and dual-frequency output extension are introduced to describe the orthogonal polarized characters of the laser. The feedback effects are coupled into the inner-cavity of the laser using F-P cavity theory. The multi-beam interference idea is used for different feedback level. This orthogonal polarized laser feedback theory model can explain phenomena, such as the intensity branches and obvious humpback on the opposite side of the two orthogonal polarized frequencies’curves appears, in frequency splitting laser with optical feedback effects. （2） Optical feedback’s effect on lasers’net gain characters is studied theoretically and experimentally. It is discovered that the feedback beam’s modulation on lasers’inner-cavity results in①Periodic waves superpose on Gauss-shape net gain curve of lasers without optical feedback, and the period of these waves are determinate by the proportion between the inner-cavity length and external cavity length.②The net gain curve is broadened which enlarges the bandwidth of lasers output light.③The values of lasers’net gain are increased and bring big modulated depth of lasers intensities. These are physical principles behind the novel phenomena of optical feedback effects in frequency splitting lasers. （3） The main factors that impact the form of feedback fringes are studied. The amplitude of feedback fringes increases as the reflectivity of feedback mirror increasing. For the same reflectivity, the longer the external cavity length is, the greater the amplitude will be. The phase delay between the two orthogonal polarized frequencies is determinate by the frequency difference and external cavity length. The experimental results are in good agreement with theoretical analysis. （4） Two proposals are brought up to stabilize the lasers’frequencies dynamically with feedback effects, peak value detection and mean value comparation. Combined with the static frequency stabilization technology, the final method of feedback displacement measuring system’s frequency stabilization is presented. Then the system can work quickly and accurately in the large-scale and non-laboratory environment. These results have practical significance. （5） Frequency stabilized displacement measuring system with feedback effects is developed. Calibrated with the Aglient5529A interferometer, the specifications of the system are: range is 100mm, the measurement unit is 79.106291nm, measuring speed is 36μm/s～3cm/s , standard deviation of the whole range is < 0.4μm, linearity error is around 7×10^-6 and dynamic frequency stability is better than 10?7 . This system has strong anti-disturbance ability and simple structure, be easy to use and non-contact measurement, which can bring a good application prospect.更多还原