光参量啁啾脉冲放大(OPCPA)若干关键单元技术的研究
文献类型：学位论文
| 作者 | 郭晓杨 |
| 学位类别 | 博士 |
| 答辩日期 | 2015 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 李儒新 |
| 关键词 | 光参量啁啾脉冲放大，超短超强激光技术，相位匹配，增益带宽，展宽压缩，对比度 |
| 其他题名 | Research on Some Key Technologies on Optical Parametric Chirped Pulse Amplification (OPCPA) System |
| 中文摘要 | 超短超强激光技术的发展为人类创造出前所未有的综合性的实验室尺度极端物理条件，在强场激光物理等基础研究和高能粒子加速等前沿应用方面具有重要意义。由于光学参量啁啾脉冲放大(Optical parametric chirped pulse amplification, OPCPA)具有宽的增益带宽、无增益窄化、极高的单程增益、高对比度、低热积累等优势，因此OPCPA被认为是可以进一步提升激光脉冲峰值功率至10PW乃至更高量级的主要技术路线之一。本论文结合超短超强激光系统，围绕OPCPA技术开展研究，特别对OPCPA过程中放大带宽、能量、脉冲相位和时间对比度等进行了研究。本论文主要取得了以下创新成果和研究进展： 1.提出将OPCPA过程中三波相互夹角的标准差作为评价三波光斑耦合的标准。标准差越小则三波耦合的越好，输出能量越高，反之则差。将该标准应用于PVWC(Poynting vector walk-off compensation)入射方式和TPM(Tangential phase-matching)入射方式对OPCPA过程影响的比较分析。发现当泵浦光和信号光中心波长分别为527nm和800nm时，对BBO、CLBO、DKDP等晶体来说，TPM方式三波耦合的更好。通过数值求解三维耦合波方程，发现TPM方式获得的能量更高。基于BBO晶体的OPCPA实验证实了这一结论。利用该评价标准，为设计高输出能量的OPCPA系统提供了指导。 2.首次给出了满足宽带及超宽带条件的信号光中心波长与晶体参数、泵浦光波长的经验关系。改进了估算增益带宽的解析公式。经验公式与改进型增益带宽估算公式成功的应用在了BBO、CLBO、DKDP等常见的非线性晶体上。描述带宽的经验公式和改进的增益带宽估算公式为设计宽带甚至超宽带的OPCPA系统提供了指导。 3.对描述OPCPA输出脉冲时域对比度公式进行了修正，新增了脉冲宽度及注入种子光对比度项，修正后的公式更好的符合了实验结果。另外分析了信号光光谱调制、光谱剪切对对比度的影响。对对比度的理论分析有助于设计高对比度的OPCPA系统。 4.分析了OPCPA过程中影响信号光相位的因素，发现相位失配对信号光相位的影响类似材料色散，走离及泵浦光相位的调制会给信号光相位带来畸变。如果忽略相位失配及走离的影响，饱和放大、泵浦光相位及强度的抖动均不改变信号光相位，信号光在放大过程中保持相位的恒定性。 5.给出了双轴晶体主轴折射率与单轴晶体折射率的对应关系，利用该对应关系，可以通过替换折射率的方式求解双轴晶体主平面相位匹配的匹配角度。相位匹配角度的计算实现了模块化，大大降低了相位匹配角度求解的难度与工作量。 6.使用矩阵光学的方法得到了Offner展宽器各元件横向尺寸的解析表达式，为设计实际的Offner展宽器提供了理论指导。 |
| 英文摘要 | Ultrashort ultraintense lasers generate unprecedented comprehensive laboratory scale extreme physics for people. It is significantly important in fundamental research such as high field laser physics and the frontier application of high-energy particle acceleration. Optical parametric chirped pulse amplification (OPCPA) has many advantages, such as broad gain bandwidth, no gain narrowing, high single pass gain, high contrast, low thermal load and so on. OPCPA is considered as one of the main technological route which can further improve the peak power of the laser pulses to 10 petawatt or higher. The thesis mainly focuses on the OPCPA technologies such as bandwidth, energy, phase and temporal contrast. The major innovation results and progresses are listed as below.. 1.The standard deviation of the mutual angle among three waves as the standard to evaluate three waves coupling during the process of OPCPA was suggested. The smaller the standard deviation of the mutual angel among the three waves, the better three wave coupling and high output power one will get, vice versa. When applied this standard to PVWC (Poynting vector walk-off compensation) and TPM (tangential phase-matching) configuration OPCPA, we fund that to the case of crystal like BBO、CLBO、DKDP, when the center wavelength of the pump and signal laser are 527nm and 800nm respectively, the TPM configuration’s three wave coupling is better. Through numerical solving the 3 dimensional coupled wave equation, we fund that TPM method can achieve higher energy. This conclusion has been demonstrated by BBO based OPCPA experiment. The conclusion can effectively guide us to design high output power OPCPA system. 2.The empirical formula among signal central wavelength, crystal parameter and pump wavelength under the condition of broadband and ultra-broadband OPCPA was first purposed. We also improved the analytical formula to evaluate the gain bandwidth. Both of the empirical formula and analytical formula to evaluate the gain bandwidth are applied in common crystal like BBO CLBO and DKDP. The formulas can effectively guide us during the process of design ultra-broadband OPCPA system. 3.We revised the analytical formula that describes the OPCPA output temporal contrast. The duration and contrast of the seed pulse was taken into consideration. The revised formula agrees with the experiment better. We also analyzed the influence of spectral modulation, spectral clipping on contrast. The analysis are useful to design a high contrast OPCPA system. 4.We analyzed the phase evolution in OPCPA process. The influence of phase mismatch on output signal phase is like the material dispersion. Walk off and pump phase modulation will result the output singal phase distortion. If one neglect the phase mismatch and walk off effect, one can obtain that saturation, phase and intensity jitter in pump don’t influence the signal phase. The signal phase preserves its value through the amplification process. 5.The relationship of refractive index between uniaxial crystal and biaxial crystal in principal plane are given. Using this relationship, one can use the method for uniaxial crystal to calculate the phase matching angle in biaxial crystals through replacing the refractive index. The calculation of phase match angle is modular design and decreasing the difficulty and workload. 6.The analytic expressions, which can calculate the Offner stretcher’s elements’ size, are obtained by matric optics. The analytic expressions are useful to design a practical Offner stretcher. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15924]  |
| 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 | 郭晓杨. 光参量啁啾脉冲放大(OPCPA)若干关键单元技术的研究[D]. 中国科学院上海光学精密机械研究所. 2015. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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