Ultrafast laser and electron pulses for high resolution imaging

用于高分辨率成像的超快激光和电子脉冲

• 批准号: RGPIN-2015-04753
• 负责人: Piché, Michel
• 金额: $ 2.55万
• 依托单位: Université Laval
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=662138
• 关键词: Ultrafast; laser; electron; pulses; resolution

Lasers have impacted science, engineering and medicine in a transformative way. Lasers have opened new avenues for fundamental research and generated practical outcomes that have changed our daily life. Lasers have enabled new industrial processes and medical treatments and have triggered the present age of information. Lasers have allowed exploring new states of matter at unprecedented time scales. Laser systems generate powerful beams that can be positioned with sub-wavelength accuracy and have enabled microscopy tools with unmatched resolution. Nowadays laser science is moving towards fiber lasers that are compact and efficient. However propagation of optical signals in optical fibers leads to nonlinear effects that must be carefully managed, especially with pulses of short duration. The effective bandwidth of fiber lasers inhibits the generation of pulses of duration lasting a few optical cycles. In the coming mandate we will explore methods to resolve the issues raised by the latter effects that have limited the use of fiber laser systems. Our proposal will also address how properly structured laser signals can be used for high resolution imaging with laser scanning optical microscopes and laser accelerated electrons beams.***1. Shorter and more powerful pulses from fiber laser systems. We will use a cavity design with a pair of chirped fiber Bragg gratings to boost the energy of the pulses emitted by fiber laser oscillators. We will also design amplifiers based on Stimulated Raman Scattering to preserve the bandwidth of ultrashort pulses during amplification in order to make fiber laser systems competitive with their solid-state counterparts.***2. Superresolution in laser scanning optical microscopy. We will push the resolution limits of SLAM (Switching LAser Modes) microscopy well below the diffraction limit, down to 50 nm, using complex mode shapes and deconvolution methods. SLAM can be used with any type of modality in optical microscopy and its enhanced resolution does not require any specific laser sample interaction, contrary to most superresolution methods.***3. Particle acceleration using radially polarized laser pulses. We have introduced a scheme to directly accelerate electrons in free space using the longitudinal electric field component of ultrafast radially polarized laser pulses. We will exploit that scheme to produce electron beams suitable for high resolution imaging by means of ultrafast electron diffraction. We will explore how spatiotemporal shaping of laser pulses could be used to accelerate charged particles at laser focus in such a way as to produce a micrometer scale collider.***This research program will be realized in an environment suitable for student training. The students will benefit from many internal and external collaborations, as well as interactions with industry.**

激光以变革性的方式影响了科学，工程和医学。激光为基础研究开辟了新的途径，并产生了改变我们日常生活的实践结果。激光已经实现了新的工业过程和医疗治疗，并触发了当前的信息时代。激光允许在前所未有的时间尺度上探索新的物质状态。 激光系统会生成强大的光束，可以以次波长度的精度定位，并实现了具有无与伦比分辨率的显微镜工具。如今，激光科学正朝着紧凑而高效的纤维激光器迈进。 但是，光纤维中光信号的传播导致非线性效应必须仔细管理，尤其是持续时间短的脉冲。 纤维激光器的有效带宽抑制了持续几个光周期的持续时间脉冲的产生。 在即将到来的任务中，我们将探讨解决限制纤维激光系统使用的后一种效应提出的问题的方法。我们的建议还将解决结构化的激光信号如何用于使用激光扫描光学显微镜和激光加速电子束进行高分辨率成像。*** 1。纤维激光系统的较短，更强大的脉冲。 我们将使用带有一对chir的纤维bragg光栅的空腔设计来增强纤维激光振荡器发出的脉冲的能量。我们还将设计基于刺激的拉曼散射的放大器，以在放大过程中保留超短脉冲的带宽，以使纤维激光系统与固态对应物竞争。*** 2。激光扫描光学显微镜的乳头分辨率。我们将使用复杂的模式形状和反卷积方法来将SLAM（开关激光模式）显微镜的分辨率限制远低于衍射极限，至50 nm。 SLAM可以与光学显微镜中的任何类型的模态一起使用，其增强分辨率不需要任何特定的激光样品相互作用，与大多数超分辨率方法相反。*** 3。使用径向极化激光脉冲的颗粒加速度。我们已经引入了一种方案，该方案使用超快径向极化激光脉冲的纵向电场成分在自由空间中直接加速电子。我们将利用该方案通过超快电子衍射产生适合高分辨率成像的电子束。我们将探讨如何使用激光脉冲的时空形状来加速激光焦点的带电颗粒，以产生千分尺级对撞机的方式。***该研究计划将在适合学生培训的环境中实现。 学生将从许多内部和外部合作以及与行业的互动中受益。**