窄线宽Er:Yb共掺光纤激光泵浦1.6 μm波段拉曼光纤激光器研究
文献类型：学位论文
| 作者 | 刘军 |
| 学位类别 | 博士 |
| 答辩日期 | 2014 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 范滇元 |
| 关键词 | 高功率 Er:Yb共掺光纤激光器 拉曼光纤激光器 Tm:YAG陶瓷 体布拉格光栅（VBG） 双波长 窄线宽 同带泵浦 包层泵浦 光束净化 |
| 其他题名 | 1.6 μm Raman fiber laser pumped by narrow-linewidth Er:Yb fiber laser |
| 中文摘要 | 在光电对抗应用中，2.7 μm和4.3 μm波段的双中红外激光受到特别关注。迄今已有的技术途径都只能分别产生其中一个波段的激光，且产生方法单一、转换效率受到一定限制。新近研究表明，如果采用特定波长1.658 μm的激光作为泵浦光源，通过非线性参量过程，可以同时获得2.7 μm、4.3 μm两个有用波段的激光输出。双中红外激光方案的难点和关键在于1.658 μm这个特定波长是前所未有的、不能由稀土离子直接辐射产生。另一个特殊波段激光应用的类似例证为：在大气湍流自适应光学波前校正系统中，钠导星的信标光源所需的589.1591 nm窄带黄光激光（对应钠原子D2谱线）也是一个常规方法不能直接产生的特定波长。因此，研究解决产生各类特定波长激光的技术途径和方法，是十分必要和有意义的。作为典型事例，本论文将主要针对1.6 μm波段的需求，开展系统的理论和实验研究。 在理论研究基础上，提出并优化设计了一条具有普适意义的级联型技术路线—窄线宽1.5 μm Er:Yb共掺光纤激光泵浦1.6 μm波段拉曼光纤激光器；在实验上成功实现了覆盖1.5、1.6 μm波段的窄带、可调谐及波长锁定激光输出。获得发明专利授权。通过改变增益光纤长度，并运用体布拉格光栅（VBG）波长调谐，首次在Er:Yb共掺光纤激光器中获得了同时覆盖C-band和L-band的可调谐激光输出；运用双VBG光谱窄化技术，获得了同类技术最窄线宽小于~38 pm和19.4 W功率的激光输出。再以窄带1545 nm Er:Yb共掺光纤激光泵浦渐变折射率多模通信光纤和特殊设计的双包层拉曼光纤，应用VBG于波长调谐、波长锁定及光谱窄化，实现了1.6 μm波段10.5 W功率、同类技术最窄线宽0.1 nm的激光输出和最大37 nm的调谐范围；阐述了拉曼光纤中SRS的光束净化作用，获得近衍射极限的Stokes激光输出。论文取得一系列创新成果，发表了多篇论文报告，包括SCI论文5篇、EI论文1篇、学术会议报告2篇，以及授权发明专利一项。论文的主要内容和创新点有： 一、1.5 μm波段Er:Yb共掺光纤激光器 1. 利用VBG作为波长选择元件，采用两段不同长度（7 m、17 m）的Er:Yb共掺增益光纤，分别实现了工作波长同时覆盖C-band 和L-band的宽调谐激光输出。 该工作发表在期刊IEEE Photonics Technology Letters 25(15), 1488 (2013)上。 2. 首次将双VBG光谱窄化技术应用于Er:Yb共掺光纤激光器中，获得了中心波长为1545.3 nm、线宽小于~38 pm、功率为19.4 W的激光输出。在进一步的实验中，将双VBG以并联排列的方式应用到Er:Yb共掺光纤激光器中，实现了双波长独立的连续可调谐输出，双波长间距从0.3 nm到29.2 nm，当波长间距为0.3 nm时，获得了最大功率17.9 W输出，斜效率达28.6%。两项工作分别发在在期刊IEEE Journal of Quantum Electronics 50(2), 88 (2014)、Applied Physics Express 7(3), 032702 (2014)上。 3. 结合光纤激光器优良的散热能力与体块增益介质能量存储容量大的优点，首次将宽调谐Er:Yb共掺光纤激光作为Tm:YAG陶瓷激光器泵浦源，获得了中心波长为2013.2 nm、最大功率为3.9 W的激光输出。该工作发表在期刊Applied Physics Express 6(3), 092107 (2013)上。 二、1.6 μm波段拉曼光纤激光器 1. 对于渐变折射率多模光纤的拉曼光纤激光器，在泵浦光线性吸收近似条件下，利用朗伯函数（Lambert function）推导出了描述多模光纤中受激拉曼散射（SRS）过程的波动方程的解析解，并将其应用到实际的拉曼光纤激光器设计和参数优化中，取得了较好的效果。 2. 将波长锁定的1545 nm Er:Yb共掺光纤激光器作为泵浦源，在基于普通渐变折射率多模通信光纤和特殊设计的双包层拉曼光纤的拉曼光纤激光器中分别实现了近衍射极限的1.658 μm Stokes激光输出。阐述了渐变折射率多模光纤中SRS的光束洁净作用，分析了阶跃型折射率多模光纤中不存在该光束净化作用的原因。 3. 在基于渐变折射率光纤的拉曼光纤激光器中，自由运转状态下获得了最高功率为12.3 W的激光输出，利用VBG波长锁定后，输出激光线宽仅为~0.1 nm，这是目前所报道的瓦量级拉曼光纤激光器中所获得的最窄线宽；波长调谐运转时获得了从1638.5 nm到1675.1 nm共37 nm的调谐范围，这也是拉曼光纤激光器相当功率输出下最宽的波长调谐范围。更宽的波长调谐范围可望通过改变泵浦源的工作波长实现。该工作发表在期刊Optics Express 22(6), 6605 (2014)上，且该可调谐拉曼光纤激光器已获发明专利授权（授权号：CN 102761048）。 4. 对包层泵浦的拉曼光纤激光器进行了初步的实验探索研究。阐述了双包层拉曼光纤参数设计的基本准则和双包层拉曼光纤中的SRS和模式激发过程，并最终制成双包层拉曼光纤。在自由运转和VBG波长锁定的包层泵浦拉曼光纤激光器中分别实现了功率为13.2 W、10.4 W 的1.658 μm Stokes激光输出。对包层泵浦拉曼光纤激光器的进一步功率定标放大给出了分析和讨论。 |
| 英文摘要 | Laser sources operated at 2.7 μm and 4.3 μm spectral regions have attracted considerable attention in applications involving mid-IR countermeasures. As far as I am concerned, only one wavelength of this dual-mid-IR band (either 2.7 μm or 4.3 μm) can be acquired under the present lasing schemes, which greatly limits the conversion efficiency. However, our recent research indicates that an effective scheme can be achieved to generate laser emissions at these two mid-IR wavelengths simultaneously. That is, using laser sources operating at 1.658 μm as a pump source for OPO/OPA, then the 2.7 μm signal and 4.3 μm idler wavelengths will be yielded through the nonlinear frequency conversion process simultaneously. The proposed lasing scheme for the dual mid-IR wavelengths generation suffers from the lack of pump source at this particular wavelength. Laser emissions at 1.658 μm are unprecedented and cannot be obtained by traditional stimulated emission of rare earth ions in laser gain medium. Another typical example is: a 589.1591 nm yellow laser with narrow linewidth, which allows resonance with the sodium D2 line and is used in laser guided star adaptive optics (LGS AO), is also a special wavelength uncovered by the traditional lasing approaches. Therefore, it will be very necessary and significant to investigate on the techniques and methods for generating laser emissions at certain special wavelengths. Considering the great demand of laser sources at 1.6 μm spectral region, this thesis mainly concentrates on the theoretical and experimental research on the 1.6 μm laser generation. Based on the theoretical analysis, we propose and demonstrate a widely available cascaded technological route to generate the 1.6 μm laser emission, which is based on the Raman fiber laser pumped by the 1.5 μm narrow linewidth Er:Yb fiber laser; We have successfully obtained narrow linewidth, tunable and fixed wavelength laser output covering the 1.5 μm and 1.6 μm spectral range in our experiment. Achievement involving the tunable Raman fiber laser was applied for patent. Widely tunable laser output covering the whole C-band and L-band was achieved by adjusting the Er:Yb gain fiber length and employing VBG as the wavelength tunable element. Applying the dual-VBG spectral narrowing technique in the Er:Yb fiber laser system, we have obtained an output power of 19.4 W with linewidth of less than ~38 pm. To the best of our knowledge, this is the narrowest spectral linewidth achieved so far based on the VBG technique in the Er:Yb fiber laser. In the Raman fiber lasers pumped by the narrow linewidth 1545 nm Er:Yb fiber laser based on the graded-index multimode fiber and specially designed double clad Raman fiber, a maximum output power of 10.5 W at 1.6 μm with narrowest linewidth of 0.1 nm and maximum wavelength tuning range of 37 nm were achieved by employing VBG as the wavelength tunable, locking and spectral narrowing element. Besides, we clarified the beam clean-up effect of SRS in graded-index multimode fibers and obtained near-diffraction-limited Stokes laser output experimentally. Some innovative results have been published in domestic and foreign academic journals including Optics Express, Applied Physics Express, IEEE Photonics Technology Letters, IEEE Journal of Quantum Electronics, and one achievement applied for patent. The main content and innovative results in our thesis are summarized as follows: Ⅰ. 1.5 μm Er:Yb fiber laser 1. Two Er:Yb co-doped fibers of different length were selected as the gain medium of Er:Yb fiber lasers and a widely wavelength tunable operation covering the whole C- and L-band was achieved by using a single VBG. This work has been published in IEEE Photonics Technology Letters 25(15), 1488 (2013). 2. The dual-VBG spectral narrowing technique was applied to the Er:Yb fiber laser system for the first time and a maximum output power of 19.4 W at 1545.3 nm with a full-width at half-maximum (FWHM) linewidth of < ∼38 pm is obtained. This work has been published in IEEE Journal of Quantum Electronics 50(2), 88 (2014). In our further experiment, high-power, dual-wavelength tunable operation of an Er:Yb co-doped fiber laser using two volume Bragg gratings arranged in parallel was achieved with the two wavelengths tuned independently. The wavelength separation for the two operating wavelengths was continuously tuned from 0.3 to 29.2 nm (0.04 to 3.7 THz) with a total output power of >13 W for a wavelength splitting range of< 20 nm. A maximum output power of 17.9 W was obtained at a wavelength separation of 0.3 nm for a launched pump power of 65.3 W, which corresponds to a slope efficiency of 28.6% with respect to the launched pump power. This work has been published in Applied Physics Express 7(3), 032702 (2014). 3. Based on the novel fiber-bulk hybrid configuration, the widely tunable Er:Yb co-doped fiber laser was employed as the pump source of a polycrystalline ceramic for the first time. A maximum output power of 3.9 W is obtained at 2013.2 nm under an 8.8 W incident pump power at the Tm: YAG absorption peak of 1620.4 nm. This work has been published in Applied Physics Express 6(3), 092107 (2013). Ⅱ. 1.6 μm Raman fiber laser 1. An explicit set of formulas for the Raman fiber lasers based on graded-index multimode fiber has been derived using the Lambert function under the approximation of linear pump absorption in the bilateral pumping regime. Besides, these solutions have been applied in the experimental optimization of Raman fiber lasers. 2. In the Raman fiber lasers pumped by the 1545 nm Er:Yb fiber laser based on the graded-index multimode fiber and specially designed double clad Raman fiber, near-diffraction-limited laser output at 1.658 μm was obtained. Besides, we clarified the beam clean-up effect of SRS in graded-index multimode fibers and explained why this effect does not exist in step-index multimode fibers. 3. In the free-running Raman fiber laser based on a graded-index multimode fiber, a maximum output power of 12.3 W was obtained while the fixed-wavelength laser yielded a maximum output power of 10.5 W at 1658.3 nm with a FWHM linewidth of ~0.1 nm. To the best of our knowledge, this is the narrowest lasing linewidth from Raman fiber lasers with comparable output power level. For the wavelength-tunable Raman fiber laser, a wavelength tuning range of 37 nm from 1638.5 to 1675.1 nm is obtained with a maximum output power of 3.6 W at 1658.5 nm. This is also the broadest wavelength tuning range in Raman fiber lasers with comparable output power. Broader wavelength tuning range can be obtained by adjusting the pump wavelength. This work has been published in Optics Express 22(6), 6605 (2014), and this tunable Raman fiber laser based on VBG was applied for patent (CN 102761048). 4. A preliminary exploration to the experimental work of cladding-pumped Raman fiber lasers was given in the end. In this section, we described the basic rule of double clad Raman fiber design and the SRS process in double clad Raman fiber. Based on the specially designed double clad Raman fiber, we constructed cladding-pumped Raman fiber lasers. Maximum output powers of 13.2 W and 10.4 W were obtained in the free-running and fixed-wavelength operating regimes, respectively. Prospect of output power scaling up of cladding-pumped Raman fiber laser sources was discussed. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15876]  |
| 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 | 刘军. 窄线宽Er:Yb共掺光纤激光泵浦1.6 μm波段拉曼光纤激光器研究[D]. 中国科学院上海光学精密机械研究所. 2014. |
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来源：上海光学精密机械研究所
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