Single-shot ultrafast optical imaging

Single-shot ultrafast optical imaging can capture two-dimensional transient scenes in the optical spectral range at ≥100 million frames per second. This rapidly evolving field surpasses conventional pump-probe methods by possessing real-time imaging capability, which is indispensable for recording nonrepeatable and difficult-to-reproduce events and for understanding physical, chemical, and biological mechanisms. In this mini-review, we survey state-of-the-art single-shot ultrafast optical imaging comprehensively. Based on the illumination requirement, we categorized the field into active-detection and passive-detection domains. Depending on the specific image acquisition and reconstruction strategies, these two categories are further divided into a total of six subcategories. Under each subcategory, we describe operating principles, present representative cutting-edge techniques, with a particular emphasis on their methodology and applications, and discuss their advantages and challenges. Finally, we envision prospects for technical advancement in this field

A trillion frames per second: the techniques and applications of light-in-flight photography

Cameras capable of capturing videos at a trillion frames per second allow to freeze light in motion, a very counterintuitive capability when related to our everyday experience in which light appears to travel instantaneously. By combining this capability with computational imaging techniques, new imaging opportunities emerge such as three dimensional imaging of scenes that are hidden behind a corner, the study of relativistic distortion effects, imaging through diffusive media and imaging of ultrafast optical processes such as laser ablation, supercontinuum and plasma generation. We provide an overview of the main techniques that have been developed for ultra-high speed photography with a particular focus on `light-in-flight' imaging, i.e. applications where the key element is the imaging of light itself at frame rates that allow to freeze it's motion and therefore extract information that would otherwise be blurred out and lost.Comment: Published in Reports on progress in Physic

Single-shot ultrafast optical imaging

Single-shot ultrafast optical imaging can capture two-dimensional transient scenes in the optical spectral range at ≥100 million frames per second. This rapidly evolving field surpasses conventional pump-probe methods by possessing real-time imaging capability, which is indispensable for recording nonrepeatable and difficult-to-reproduce events and for understanding physical, chemical, and biological mechanisms. In this mini-review, we survey state-of-the-art single-shot ultrafast optical imaging comprehensively. Based on the illumination requirement, we categorized the field into active-detection and passive-detection domains. Depending on the specific image acquisition and reconstruction strategies, these two categories are further divided into a total of six subcategories. Under each subcategory, we describe operating principles, present representative cutting-edge techniques, with a particular emphasis on their methodology and applications, and discuss their advantages and challenges. Finally, we envision prospects for technical advancement in this field

Roadmap on spatiotemporal light fields

Spatiotemporal sculpturing of light pulse with ultimately sophisticated structures represents the holy grail of the human everlasting pursue of ultrafast information transmission and processing as well as ultra-intense energy concentration and extraction. It also holds the key to unlock new extraordinary fundamental physical effects. Traditionally, spatiotemporal light pulses are always treated as spatiotemporally separable wave packet as solution of the Maxwell's equations. In the past decade, however, more generalized forms of spatiotemporally nonseparable solution started to emerge with growing importance for their striking physical effects. This roadmap intends to highlight the recent advances in the creation and control of increasingly complex spatiotemporally sculptured pulses, from spatiotemporally separable to complex nonseparable states, with diverse geometric and topological structures, presenting a bird's eye viewpoint on the zoology of spatiotemporal light fields and the outlook of future trends and open challenges.Comment: This is the version of the article before peer review or editing, as submitted by an author to Journal of Optics. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from i

Hyperspectral Compressive Wavefront Sensing

Presented is a novel way to combine snapshot compressive imaging and lateral shearing interferometry in order to capture the spatio-spectral phase of an ultrashort laser pulse in a single shot. A deep unrolling algorithm is utilised for the snapshot compressive imaging reconstruction due to its parameter efficiency and superior speed relative to other methods, potentially allowing for online reconstruction. The algorithm’s regularisation term is represented using neural network with 3D convolutional layers, to exploit the spatio-spectral correlations that exist in laser wavefronts. Compressed sensing is not typically applied to modulated signals, but we demonstrate its success here. Furthermore, we train a neural network to predict the wavefronts from a lateral shearing interferogram in terms of Zernike polynomials, which again increases the speed of our technique without sacrificing fidelity. This method is supported with simulation-based results. While applied to the example of lateral shearing interferometry, the methods presented here are generally applicable to a wide range of signals, including Shack-Hartmann-type sensors. The results may be of interest beyond the context of laser wavefront characterization, including within quantitative phase imaging

Programmable optics for ultrashort pulse management: devices and applications

The contribution of the present report to the field of ultrashort optics has several aspects: from the development of new optical devices for ultrashort pulse management, to the application of those devices for triggering laser-matter interaction processes. In this sense, the key point of this Thesis is the use of reconfigurable phase-only SLMs based on LCOS technology for spatial and temporal shaping of femtosecond pulses. The management of femtosecond pulses demands specific strategies to obtain the desired output response while preventing undesirable distortions. Our results show that programmable diffractive optics encoded in SLMs is a powerful tool for ultrashort (~30 fs) beam management. The reconfigurable nature of SLMs allows wavefront control of an input pulsed beam at a micro scale level. In this way, we have developed devices for transferring amplitude and/or phase maps onto the spatial and temporal profile of an ultrashort pulse. Moreover, our proposals result in very compact optical devices, allowing easy-to-align setups especially suitable for non-expert users. We believe that this fact may promote the use of ultrafast technology in many different scientific fields that demands user-friendly devices for ultrashort pulse control