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题名	强场激光诱导的空气激光产生及调控
作者	井晨睿
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	程亚
关键词	飞秒激光成丝 空气激光 分子电离 望远镜系统聚焦 啁啾控制 高振动激发态
其他题名	Generation and manipulation of an air laser induced by intense femtosecond laser pulses
中文摘要	随着飞秒激光技术的迅猛发展，飞秒激光向着脉宽更短、能量更高、光强 更强等方向上突破。在超快强激光条件下，光与物质的相互作用呈现出非线性 和非微扰的特征，并展现出一系列的新奇现象，如库仑爆炸，隧穿电离，多光 子电离，高次谐波，飞秒激光成丝等。 近年来人们发现，在强激光与物质相互作用的过程中，分子可以被激发形 成粒子数反转，从而产生空气激光。目前一系列的研究结果表明，实验上在多 种介质中观测到的前向和背向的空气激光主要是基于自发辐射放大或受激种子 放大两种完全不同的物理机制。其中基于粒子数反转受激种子放大过程产生的 空气激光，其具有窄线宽，高信噪比，良好的相干性以及偏振特性等诸多优点， 因而在实时动态的探测物质组成成分，以及远程遥感中具有重要的潜在应用。 基于上述背景，本论文工作瞄准强场激光与分子气体相互作用诱导产生的 超快空气激光这一光学前沿领域，着重实现在远距离位置处的空气激光的产生， 以及采用全光学手段调控空气激光的强度，实现空气激光波长的切换，从而推 进空气激光在远程遥感以及大气成分探测中的实际应用。 本论文主要工作和创新性成果如下： 1.提出了强场激光诱导的远程空气激光产生方法：望远镜系统聚焦。利用 飞秒激光泵浦，改变传统单透镜聚焦为望远镜系统聚焦，突破了传统聚焦模式 下空气激光产生的距离限制，拓展了空气激光的工作距离，实现了远距离位置 处空气激光的产生。 2. 提出了强场激光诱导的空气激光调控手段：啁啾脉冲控制。利用单束飞 秒激光泵浦，通过改变泵浦光啁啾，发现同一谱带不同振动态跃迁产生的空气 激光强度随着泵浦光啁啾的变化不同。利用双色场泵浦-探测方案，证实了单束 飞秒激光诱导的空气激光谱线强度随啁啾变化不同来源于种子的不同。 3. 实现了强场激光诱导的空气激光波段拓展：高振动激发态空气激光。报 道了单束 800 nm 圆偏振飞秒激光在低压氮气中诱导的高振动激发态空气激光。 利用泵浦-探测方案，测量了不同气压条件下产生的高振动激发态空气激光的时 间演化动力学过程，并指出电子碰撞激发为高振动态空气激光的产生途径。
英文摘要	With the rapid development of femtosecond laser technology, recent progress in ultrafast optics has led to the generation of femtosecond laser pulses which have shorter durations and higher energies. Using such intense laser pulses, ultrafast lasermatter interactions possess the nonlinear and non-perturbation characteristics, which lead to a lot of intriguing phenomena, such as Coulomb explosion, tunneling ionization, multiphoton ionization, high order harmonic generation, femtosecond filamentation, etc. Recently, it has been discovered that, by exposure to the ultrafast intense laser field, the molecules in air can be excited to generate population inversion, thereby generating the air laser. Early results have shown that the generation of air lasers can be achieved through two different mechanisms, i.e. amplified spontaneous emission and stimulated seed amplification. In particular, the air laser based on the stimulated seed amplification has several distinct advantages such as low divergence, narrow bandwidth, high signal to noise ratio, good coherence and determinative polarization, which are highly desirable for remote sensing Based on the above-mentioned consideration, in this thesis, we focus on the generation of laser in remote air at farther distance, and manipulation of the air laser wavelength using an all optical approach, which will benefit the practical applications of air laser in remote sensing and atmospheric detection. The main results and innovations of the thesis are listed as follows: 1. We demonstrate the new method-telescope optics as the focusing method to generate air laser induced by intense femtosecond laser pulses. By using a telescope, the limition of distance where the lasing action take place can be overcome and the air laser can be controlled to occur at remotely designated distance. 2. A new method to achieve the dynamic wavelength switching of a remote nitrogen or air laser by chirped femtosecond laser pulses is proposed. As the chirp of the pump laser pulses varies from negative to positive, the intensities of the lasing signals at 391 and 428 nm show different chirp-dependent behaviors. By introducing an external seed for a pump–probe measurement, we verify that the different behavior of lasing emissions on the pump chirp is ascribed to the different self-generated seed sources produced in the plasma channel. 3. We demonstrate the free-space air lasing from highly excited vibrational states with ultrashort intense 800 nm laser pulses. The highly excited vibrational laser emissions, which can be achieved only at relatively low pressures, show a strong dependence on the ellipticity of the pump pulses. By introducing an external seed for pump–probe measurement, we reveal the pressure-dependent gain dynamics of these lasing actions from highly excited vibrational states. Our experimental observations suggest that impact excitation from high-energy electrons should be the dominant mechanism responsible for the lasing actions from these highly excited vibrational states of nitrogen ions.
语种	中文
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/15920]
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	井晨睿. 强场激光诱导的空气激光产生及调控[D]. 中国科学院上海光学精密机械研究所. 2015.

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