Characteristics and Applications of Spatiotemporally Focused Femtosecond Laser Pulses

Jing, Chenrui; Wang, Zhaohui; Cheng, Ya

doi:10.3390/app6120428

Cited by 16 publications

(10 citation statements)

References 37 publications

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“…Recently, temporal focusing has been achieved through static scattering media 10 , which has sparked interest in deep biomedical imaging. In addition, the strong intensity localization has made it an attractive tool for material processing 11 , which has led to extensive studies of elusive physics mechanisms of the strong-field interaction with matter 12 . Considering the stochastic (e.g., time reversal of dynamic speckle patterns to produce temporal focusing in live biological tissue 13 ) and non-repeatable (e.g., micromachining using temporal focusing in glass 14 ) nature of these transient phenomena, visualizing temporal focusing in real time (i.e., at its actual time of occurrence) becomes a prerequisite for investigating and further utilizing them.…”

Section: Introductionmentioning

confidence: 99%

Single-shot real-time femtosecond imaging of temporal focusing

2018

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While the concept of focusing usually applies to the spatial domain, it is equally applicable to the time domain. Real-time imaging of temporal focusing of single ultrashort laser pulses is of great significance in exploring the physics of the space–time duality and finding diverse applications. The drastic changes in the width and intensity of an ultrashort laser pulse during temporal focusing impose a requirement for femtosecond-level exposure to capture the instantaneous light patterns generated in this exquisite phenomenon. Thus far, established ultrafast imaging techniques either struggle to reach the desired exposure time or require repeatable measurements. We have developed single-shot 10-trillion-frame-per-second compressed ultrafast photography (T-CUP), which passively captures dynamic events with 100-fs frame intervals in a single camera exposure. The synergy between compressed sensing and the Radon transformation empowers T-CUP to significantly reduce the number of projections needed for reconstructing a high-quality three-dimensional spatiotemporal datacube. As the only currently available real-time, passive imaging modality with a femtosecond exposure time, T-CUP was used to record the first-ever movie of non-repeatable temporal focusing of a single ultrashort laser pulse in a dynamic scattering medium. T-CUP’s unprecedented ability to clearly reveal the complex evolution in the shape, intensity, and width of a temporally focused pulse in a single measurement paves the way for single-shot characterization of ultrashort pulses, experimental investigation of nonlinear light-matter interactions, and real-time wavefront engineering for deep-tissue light focusing.

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Section: Introductionmentioning

confidence: 99%

Single-shot real-time femtosecond imaging of temporal focusing

2018

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“…In this way, the initial transform-limited pulse transiently restores itself at the focus while being stretched either before or after the focus, enabling shortening of the focal depth in terms of the peak intensity. [12,13] Here, we show that when combining the SSTF with TPP, the nonlinear threshold effect in TPP uniquely allows for producing multi-scale 3D structures with a variable fabrication resolution in an alignment-free manner. This is benefitted from the fact that the size of laser affected volume with the STTF spot linearly depends on the power of the laser beam, making it extremely easy to dynamically tune the fabrication resolution during the continuous writing process.…”

Section: Introductionmentioning

confidence: 80%

High-throughput multi-resolution three dimensional laser printing

Tan¹,

Chu²,

Wang³

et al. 2018

Phys. Scr.

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Throughput and resolution are both of critical importance for modern manufacturing, however, they are usually contradictory with each other. Here, a highthroughput high-resolution three dimensional (3D) printing is demonstrated by incorporating a simultaneous spatiotemporal focusing (SSTF) scheme in two-photon polymerization (TPP).Remarkably, the SSTF can ensure generation of a spherical focal spot of which the size depends linearly on the laser power. Thus, the resolution can be continuously adjusted from sub-10 μm to ~40 μm by only increasing the laser power. A multi-scale 3D structure is fabricated using this technique, for which the regions of coarse and fine feature sizes are produced at high and low resolutions, respectively.Received: ((will be filled in by the editorial staff)) Revised: ((will be filled in by the editorial staff)) Published online: ((will be filled in by the editorial staff)) Keywords: (femtosecond laser two photon polymerization, multiscale 3D printing, simultaneous spatiotemporal focusing)

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“…A femtosecond laser, which has the advantage of precise ablation with little or no thermal impact on surrounding materials [11,12], can overcome the above shortcomings as an ultra-short-pulse laser. A femtosecond laser has been widely used in many fields, such as the processing of various materials [13,14] and the fabrication of micro-components [15][16][17], because of its unique processing characteristics.…”

Section: Introductionmentioning

confidence: 99%

Ablation and Patterning of Carbon Nanotube Film by Femtosecond Laser Irradiation

Yin

2019

Applied Sciences

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Carbon nanotube (CNT) film can be used as thin film electrodes and wearable electronic devices due to their excellent mechanical and electrical properties. The femtosecond laser has the characteristics of an ultra-short pulse duration and an ultra-high peak power, and it is one of the most suitable methods for film material processing. The ablation and patterning of CNT film are performed by a femtosecond laser with different parameters. An ablation threshold of 25 mJ/cm2 was obtained by investigating the effects of laser pulse energy and pulse number on ablation holes. Raman spectroscopy and scanning electron microscope (SEM) were used to characterize the performance of the pattern groove. The results show that the oligomer in the CNT film was removed by the laser ablation, resulting in an increase in Raman G band intensity. As the laser increased, the ablation of the CNTs was caused by the energy of photons interacting with laser-induced thermal elasticity when the pulse energy was increased enough to destroy the carbon–carbon bonds between different carbon atoms. Impurities and amorphous carbon were found at and near the cut edge while laser cutting at high energy, and considerable distortion and tensile was produced on the edge of the CNTs’ groove. Furthermore, appropriate cutting parameters were obtained without introducing defects and damage to the substrate, which provides a practical method applied to large-area patterning machining of CNT film.

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Characteristics and Applications of Spatiotemporally Focused Femtosecond Laser Pulses

Cited by 16 publications

References 37 publications

Single-shot real-time femtosecond imaging of temporal focusing

Single-shot real-time femtosecond imaging of temporal focusing

High-throughput multi-resolution three dimensional laser printing

Ablation and Patterning of Carbon Nanotube Film by Femtosecond Laser Irradiation

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