MRI: Development of a Phase-coherent Laser System for Attosecond Science and Precision Spectroscopy

自从近半个世纪前激光的最初发明以来，激光物理学一直沿着两条看似不同的道路发展。为了研究原子和分子动力学，发展了短脉冲、宽光谱的高功率激光器，发展了带宽很窄的连续激光器，并将其用于高分辨率光谱。频率梳技术由Hall和Hansch发明，并得到2005年诺贝尔物理学奖的认可，它将这些路径重新结合在一起，为本项目的主题--精密光谱学和动力学实验开辟了新的机会。频率梳技术允许产生仅由几个光学周期组成的激光脉冲，并且相位受到精确控制，或者相当于产生一组具有精确定义的频率的紧密间隔的颜色。该技术能够以亚周期精度控制激光场的时间演化，从而进入阿秒时间域。阿秒(十亿分之一秒)时间域是电子在原子和分子中运动的自然时间尺度。因此，阿秒照明使拍摄电子动力学快照成为可能，例如在化学反应中。直到最近，才有可能产生阿秒激光脉冲，这是一项对原子和分子物理、化学和生物学具有根本重要性的发展。该项目将开发一种多功能的相位相干激光系统，使德克萨斯农工大学在阿秒激光物理方面的研究和教育成为可能。该系统的核心是一个能够在红外光谱区产生相位稳定的短周期脉冲的高功率啁啾脉冲光参量放大器。这种脉冲将在强场激光物理实验中用作探测器。此外，它们还可以产生与驱动光场完全同步的孤立的阿秒极端紫外线(XUV)脉冲。相位稳定的几个周期的红外脉冲和同步的XUV脉冲的同时可用将为探索分子解离和分子排列的阿秒动力学提供能力。此外，还将测试利用分子以锁步方式振动和旋转的独特性质的各种想法。该系统将为德克萨斯A&A&M的大量科学和工程教职员工和学生提供宝贵的资源。该项目将为研究生和本科生提供极好的培训机会，并将培训无数应用相位相干激光系统、XUV技术和超快光学所需的劳动力。计划中的与美国和欧洲顶尖科学家的合作将为学生提供宝贵的国际经验。这一项目的成果将通过科学出版物、学术讨论会和教师和学生的会议报告来传播。将利用暑期学校、系列讲座、科学主题日等外联活动来宣传该项目，吸引最优秀的学生，并向感兴趣的公众提供信息。

0722800PaulusSince the original invention of the laser nearly half a century ago, laser physics has evolved on two seemingly divergent paths. High power lasers with short pulses and broad spectral bandwidths were developed for use studying atomic and molecular dynamics and continuous lasers with very narrow bandwidths were developed and used in high-resolution spectroscopy. The frequency comb technique - invented by Hall and Hansch and recognized by the 2005 Physics Nobel prize - brought the paths back together and opened new opportunities for precision spectroscopy and dynamics experiments, the theme of this project. The frequency-comb technique allows production of laser pulses that consist of only a few optical cycles with the phase being precisely controlled, or equivalently a set of closely spaced colors with precisely defined frequency. The technique enables control of the temporal evolution of the laser field with sub-cycle precision thus giving access to the attosecond time domain. The attosecond (a billionth of a billionth of a second) time domain is the natural time scale of electron motion in atoms and molecules. Therefore, attosecond illumination makes it possible to take snapshots of electron dynamics, e.g. in chemical reactions. Only very recently has it become possible to generate attosecond laser pulses, a development of fundamental importance for atomic and molecular physics, for chemistry and for biology.This project will develop a versatile phase-coherent laser system that will enable research and education in attosecond laser physics at Texas A&M University. The core of this system will consist of a high-power chirped-pulse optical parametric amplifier capable of generating phase-stabilized few-cycle pulses in the infrared (IR) spectral region. Such pulses will serve as probes in strong-field laser physics experiments. Furthermore, they will allow production of isolated attosecond pulses of extreme ultraviolet (XUV) radiation which are perfectly synchronized with the driving optical field. Simultaneous availability of phase-stabilized few-cycle IR pulses and synchronized XUV pulses will provide capabilities for exploring the attosecond dynamics of molecular dissociation and molecular alignment. In addition, various ideas exploiting unique properties of molecules vibrating and rotating in lockstep will be tested. The system will serve as a valuable resource to a large number of Texas A&M science and engineering faculty and students.The project will offer excellent training opportunities to graduate and undergraduate students, and will train the workforce necessary for the countless applications of phase-coherent laser systems, XUV technology, and ultra-fast optics in general. The planned collaborations with leading scientists in the US and Europe will provide the students with valuable international experience. The results of this project will be disseminated through scientific publications, colloquia, and conference presentations by faculty and students. Outreach activities such as summer schools, lecture series, science-themed days will be used to promote the project, attract the best students, and inform the interested public.