软玻璃光纤产生宽带高相干超连续谱的研究
文献类型：学位论文
| 作者 | 黄春雷 |
| 文献子类 | 博士 |
| 导师 | 廖梅松 |
| 关键词 | 光子晶体光纤 Photonic crystal fibers 非线性光纤光学 Nonlinear fibers optics 飞秒现象 Femtosecond phenomena 超连续谱产生 Supercontinuum generation |
| 其他题名 | The Study on Broadband and Highly Coherent Supercontinuum Generation in Soft-glass Fibers |
| 英文摘要 | 宽谱高相干性超连续谱能够应用于超短脉冲产生、光频率测量等领域。软玻璃具有高非线性折射率的特点，适合制作高非线性光纤，能够提高光谱的展宽且在短光纤即可完成光谱展宽过程。本文主要研究使用硅酸盐玻璃设计和制备平坦的全正色散光纤产生宽带高相干性超连续谱，并对相干特性、光谱的平坦特性、光谱应用于脉冲压缩等方面进行了研究和分析。 论文的第一章主要论述了超连续谱的研究进展及应用领域。尤其介绍了软玻璃光纤应用于超连续谱产生的研究进展，提出了课题的研究内容及思路。 第二章主要介绍了超短脉冲在光纤中传输的理论基础，各种非线性效应和非线性薛定谔方程的数值处理方法。 第三章筛选了两种折射率差合适的硅酸盐玻璃光纤。该玻璃具有很好的化学稳定性和抗析晶能力。这两种硅酸盐玻璃之间的热膨胀系数是相近的，而且它们具有相近的温度-粘度关系。设计了一款星形结构的全固态光子晶体光纤。该光纤在很宽的波长范围内具有平坦的色散曲线，且色散的绝对值较小。该光纤在1.5 μm以上的波段具有单模特性。使用堆垛法制备了该结构的光纤，采用1060 nm激光泵浦该光纤产生的超连续谱与数值模拟的结果相吻合。研究了宽度为0.5 ps的脉冲泵浦该光纤产生超连续谱。数值模拟结果表明，产生了从975 nm 到 2095 nm的超连续谱，宽度对应于超过一个倍频。该超连续谱具有很高的相干特性。在时域内，脉冲表现出完整性。该结果表明，该光纤能够满足亚皮秒脉冲泵浦产生宽带高相干性的超连续谱。商业上，亚皮秒脉冲光纤激光器较为成熟，且输出功率较大，因此，该光纤能够作为非线性介质获得宽带、高相干性、高功率输出的全光纤超连续谱源。还研究了宽脉冲泵浦产生超连续谱过程中消相干的机理。全正色散光纤产生超连续谱的过程中，消相干主要来源于喇曼放大种子噪声。在短脉冲条件下，自相位调制和光波分裂快速发生，最大喇曼增益的位置不断变化而不能积累噪声，因此能够保持高度的相干性。在宽脉冲泵浦条件下，喇曼放大种子噪声能够被有效积累并对脉冲的相干特性产生影响。喇曼放大种子噪声首先在泵浦波长的短波一侧积累；当更长脉冲泵浦时，被放大噪声的积累会向长波长一侧蔓延。相应地，在喇曼放大噪声的影响下，相干性越差的超连续谱在频域和时域都体现出更丰富的精细结构。 第四章的研究目的是为了获得高平坦度的超连续谱。设计了一类只含有六角形元素的全固态光子晶体光纤。该光纤的结构设计灵活且适合于堆垛法制备。通过调节光纤结构和参数，获得了在很宽的波长范围内具有低绝对值且十分平坦的色散曲线。使用1060 nm激光脉冲泵浦制备好的光纤产生的超连续谱与数值模拟的结果一致，因此，模拟获得的光纤色散曲线是合理的。研究了宽脉冲泵浦只含有六角形元素的全固态光子晶体光纤产生超平坦的超连续谱。数值模拟上，使用200 fs宽度的脉冲泵浦该光纤，产生了超平坦的超连续谱。该超连续谱在1030 nm – 2030 nm范围内的强度波动仅仅只有3 dB，而且具有很高的相干特性。与已报道的结果相比，该光纤能够容许产生超平坦超连续谱的脉冲泵浦宽度是最大的。该结果表明，作为非线性介质，该光纤可用于产生宽带、高相干性、超平坦的超连续谱源。还研究了超平坦超连续谱的影响因素。结果表明，高平坦度容许的泵浦脉冲参数与光纤的特性紧密相关。合适的光纤特性可以容许更大范围参数的脉冲泵浦光纤产生超平坦的超连续谱。 第五章研究了全正色散光纤产生的超连续谱应用于脉冲压缩。系统研究了光纤的长度、脉冲的参数等因素对脉冲压缩的影响。在线性啁啾补偿的条件下，只含有六角形元素的全固态光子晶体光纤产生超平坦的超连续谱能够被压缩到13.9 fs，相当于2.69个光学周期。 最后对论文做了系统性总结，指出了研究的创新点和不足，对研究课题提出了展望。; Supercontinuum (SC) generation in optical fibers has attracted widespread attention due to outstanding applications in many fields, including ultrashort pulse generation and optical frequency metrology. Soft glasses possess higher nonlinear refractive index and are suitable for high nonlinear fibers enhancing spectral broadening in a short propagation distance. In this manuscript, silicate glasses are employed to develop all-solid photonic crystal fibers with flattened dispersion curves. SC spectra generated in the fibers have the broad bandwidth and good coherence properties. Moreover, decoherence and flatness of the spectra and ultrashort pulse generation are studied and analyzed. In the first chapter, the research and theory progress on SC generation are briefly introduced. Secondly, several outstanding applications on SC are presented. Then, current status on SC generation in soft glass fibers was reviewed. At last, the content and outline of the study are presented. The second chapter mainly introduces the basic theories on ultrashort pulses propagation in optical fibers. Several dispersive and nonlinear effects are included. The numerical model of the generalized nonlinear Schr?dinger equation (GNLSE) was taken account of. In the third chapter, we selected two thermally matched silicate glasses with a fair refractive index contrast. The two silicate glasses had outstanding chemical stability as well as similar thermos-physical and mechanical properties. Based on the glasses, we designed an asterisk-shaped photonics crystal fiber presenting a single mode property above 1.5 μm and a low, ultra-flat and all-normal dispersion in a wide wavelength range. The experimental spectrum generation in the fiber pumped at 1.06 μm agreed with that of the numerical simulation. We numerically investigated the SC generation in the fiber pumped at 1.55 μm. The spectral bandwidth at the -20 dB level covered from 975 nm to 2095 nm, corresponding to more than one octave. The integrality of the pump pulses was retained during broadening in the time domain, and thus the SC pulses possess high coherence. The commercially erbium-doped fiber lasers in the sub-picosecond regime are more technologically mature. Therefore, the asterisk-shaped all-solid MOF pumped in a sub-picosecond duration regime is a useful candidate for broadband, high-power and all-fiber SC sources with high coherence, thus enhancing the mobility and potential application of SC sources. In addition, decoherence of the SC generation in fibers pumped with broad pulses is studied in the third chapter. For short pump pulses, spectral broadening in SPM and OWB was such fast that the position of the maximum Raman gain shifted rapidly. Therefore, Raman-amplified noise cannot accumulate enough in the spectrogram and was not significant. For long pump pulses, the spectral broadening in SPM and OWB was slow and Raman-amplified noise in the spectrogram had a chance to build up dramatically. As a result, the accumulated noise became significant to degrade the coherence. In the spectral broadening dynamics, decoherence firstly occurred in the short wavelength regime near pump wavelength. For longer pump pulses, decoherence spread towards the long wavelength regime. The SC spectra possess more fine structures in time and spectral domain due to Raman-amplified noise. In the fourth chapter, we are dedicated to obtaining SC with high flatness. An all-solid photonic crystal fiber composed only of hexagonal glass elements was proposed and developed using the stack-and-draw method. Based on a couple of silicate glasses, the optimized fiber exhibited ultraflat all-normal dispersion covering a wide wavelength interval of approximately 1.55 μm. The experimental spectrum generated at 1.06 nm well agreed with that of the numerical simulation, despite the peak around the pump wavelength. A broadband SC spectrum with flatness < 3 dB, spanning from approximately 1030 to 2030 nm (corresponding to nearly one octave), is numerically generated in the fiber with 200 fs pump pulses at 1550 nm. Compared with results of previous reports, the pump pulse duration is much longer. The results indicate that the fiber as a nonlinear medium can be capable of generating broadband, ultraflat and highly coherent SC spectra. Besides, the influence of fiber and pump pulse parameters on the spectral flatness is also studied. The results indicate that propagation length, broad pulse duration and high peak power seriously affects the spectral flatness. Therefore, a fiber with special properties can provide a large pump pulse parameter region to generate SC spectra with high flatness. In the fifth chapter, we study pulse recompression of the SC pulses propagating all-normal dispersion fiber. We mainly study the influence of the propagation distance and pump pulse parameters on pulse recompression of the SC pulses. With second-order dispersion compensation, the full width of the half maximum of the pulse is 13.9 fs, corresponding to 2.69 optical cycles at a central wavelength of 1550 nm, and the pulse exhibits a relatively good quality. At last, we conclude the manuscript in a system and point out the innovations and shortages. |
| 学科主题 | 材料学 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/31139]  |
| 专题 | 中国科学院上海光学精密机械研究所 |
| 作者单位 | 中国科学院上海光学精密机械研究所 |
| 推荐引用方式 GB/T 7714 | 黄春雷. 软玻璃光纤产生宽带高相干超连续谱的研究[D]. |
入库方式： OAI收割
来源：上海光学精密机械研究所
浏览0
下载0
收藏0
其他版本
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。