半导体激光器光电负反馈线性调频技术研究
文献类型：学位论文
| 作者 | 吴映 |
| 学位类别 | 硕士 |
| 答辩日期 | 2013 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 瞿荣辉 |
| 关键词 | 激光调频，线性调频，自外差测量，光电负反馈 |
| 其他题名 | Research on Optical Chirp Linearization Technique of Semiconductor Lasers by an Optoelectronic Feedback Loop |
| 中文摘要 | 激光线性调频技术能使激光器输出的光频率在一定时间内线性变化。频率线性变化的单模激光光源在调频连续波（FMCW）激光雷达、光频域反射计（OFDR）、3D成像、相干原子操纵、相干光谱分析、高分辨率光谱仪等领域有广泛应用。光电负反馈线性调频技术有着控制精度高、调谐速率稳定、能实现大调谐速率、能实时监控等优势，是线性调频技术的当前研究热点。基于这一背景，本论文围绕半导体激光器的光电负反馈线性调频技术进行了研究，主要内容如下： 1. 研究了自外差测量的输出信号特性，从理论上分析了激光器噪声对输出信号频谱成分的影响，并从实验上研究了延迟线长度和激光器线宽对自零差测量输出信号的时域影响。延迟线长度影响调频激光的各种噪声成分在测量信号中的体现，也影响调频的测量精度。基于这一研究结果，针对大线宽激光器提出了长延迟线的测量方法。设计鉴频反馈电路，实现了半导体激光器的线性调频，线性调频范围10GHz，调谐速率300MHz/ms。反馈后拍频频率变化量显著减小。利用自零差测量和希尔伯特变换进行数据处理，分析了光频变化，考察了激光器的调谐特性及调谐非线性，实验结果表明反馈后光频随时间变化的线性度显著提高。本文设计的鉴频反馈技术可以大大简化系统复杂性。加长的光纤延迟线可以避免激光器噪声对鉴频的影响，使该系统对激光器的适应范围更广。 2. 针对高相干的激光应用，本文还研究了基于光学锁相的光电负反馈线性调频技术。分别从时域和频域上分析了线性调频负反馈系统，特别是进行了详细的频域分析。给出了各部分元件的传递函数，包括自零差测量结构的传递函数，最终给出系统的传递函数，分析了环路稳定性。给出环路噪声模型，分析噪声对环路锁定的影响。还分析了半导体激光器的频率响应和环路延时对环路带宽的影响。设计了一个光学锁相环，鉴相电路将调频非线性转换成误差信号进行反馈锁定，环路锁定后误差信号趋近于零。分析了环路锁定前后的光电探测器输出的拍频信号的频谱。光频随时间的变化曲线表明环路锁定后激光频率变化的线性度显著提升。激光器调频范围超过6GHz，调谐速率700MHz/ms。 |
| 英文摘要 | Optical chirp linearization enables the optical frequency of the laser to vary line-arly over a certain period of time. Monomode laser sources with linear frequency chirping capabilities are widely used in many fields, including frequency modulated continuous wave (FMCW) lidar, optical frequency domain reflectometry (OFDR), 3D imaging, coherent atom manipulation, and coherent spectroscopy. Optical chirp line-arization by an optoelectronic feedback loop makes it possible to control frequency tuning with high precision, stabilize tuning rate, achieve large tuning rate and to mon-itor tuning error in real-time. The advantages of this technique have made it become a research hotspot. Under this background, this thesis is dedicated to the study of optical chirp linearization technique of semiconductor lasers by an optoelectronic Feedback Loop. The main contents are as follows: 1. Output signal characteristics of self-heterodyne measurement has been studied. An output signal spectrum analysis considering laser phase noise is conducted, and the influence of delay time and laser line width on output signal is studied in experiment. Delay time affects both the different noise components induced by chirped laser in the measurement signal, and the the measurement accuracy. Based on these results, a long delay line measurement method for large line width lasers is proposed. With the specially designed frequency discriminator, frequency sweep of a semiconductor laser is linearized. A linear optical frequency tuning rang over 10 GHz is realized, the tuning rate remains at 300MHz/ms. The analysis of beat frequency indicates that beat frequency variation is significantly reduced after feedback. An optical frequency measurement is performed by self-homodyne measurement and Hilbert transform analysis, which proves a more linear frequency variation after feedback. The method based on frequency discrimination can greatly simplify the complexity of the system. Longer fiber delay line avoids signal degradation induced by laser noise, which makes the system adaptable to a wider range of lasers. 2. Aiming at highly coherent laser applications, the thesis also studies the chirp linearization technique based on optical phase-locked loops. The negative feedback system is both studied in time domain and frequency domain. Transfer function of each part of the system is provided, including the self-homodyne measurement struc-ture. Ultimately the transfer function of the system is given which leads to a loop sta-bility analysis. Various noise sources affecting the loop performance is studied as well as the frequency response of the semiconductor laser and the loop delay. An optical phase lock loop is designed. The phase detector provides an error signal according to tuning nonlinearity to keep the loop in-lock. When the loop is in-lock, the error signal approaches zero. Analysis of beat signals before and after feedback is performed. The optical frequency is measured; experimental results show that the linearity of fre-quency sweep is significantly improved by the loop. A whole linear tuning range of 6 GHz is achieved, the tuning rate remains at 700MHz/ms. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16745]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 吴映. 半导体激光器光电负反馈线性调频技术研究[D]. 中国科学院上海光学精密机械研究所. 2013. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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