Topic
Femtosecond
About: Femtosecond is a research topic. Over the lifetime, 35106 publications have been published within this topic receiving 691405 citations. The topic is also known as: 1 E-15 s & fs.
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TL;DR: Using time-stretch dispersive Fourier transform (TDFT) as mentioned in this paper, the authors directly observed the spectro-temporal dynamics of the mode-locking transition on a single-shot basis over long record lengths of ∼900,000 consecutive pulses.
Abstract: Using time-stretch dispersive Fourier transform, scientists directly observe the spectro-temporal dynamics of the mode-locking transition on a single-shot basis over long record lengths of ∼900,000 consecutive pulses.
315 citations
TL;DR: In this article, the authors present a simple picture using the Bloch Equation of femtosecond Pulses and demonstrate how to manipulate and change the characteristics of laser pulses.
Abstract: Laser Basics.- Pulsed Optics.- Methods for the Generation of Ultrashort Laser Pulses: Mode-Locking.- Further Methods for the Generation of Ultrashort Optical Pulses.- Pulsed Semiconductor Lasers.- How to Manipulate and Change the Characteristics of Laser Pulses.- How to Measure the Characteristics of Laser Pulses.- Spectroscopic Methods for Analysis of Sample Dynamics.- Coherent Effects in Femtosecond Spectroscopy: A Simple Picture Using the Bloch Equation.- Terahertz Femtosecond Pulses.- Coherent Control in Atoms, Molecules and Solids.- Attosecond Pulses.
312 citations
TL;DR: In this article, the concepts and principles of femtosecond laser 3D micro-and nanofabrication are described and a comprehensive review on the state-of-the-art, applications, and the future prospects of this technology is presented.
Abstract: The rapid development of the femtosecond laser has revolutionized materials processing due to its unique characteristics of ultrashort pulse width and extremely high peak intensity. The short pulse width suppresses the formation of a heat-affected zone, which is vital for ultrahigh precision fabrication, whereas the high peak intensity allows nonlinear interactions such as multiphoton absorption and tunneling ionization to be induced in transparent materials, which provides versatility in terms of the materials that can be processed. More interestingly, irradiation with tightly focused femtosecond laser pulses inside transparent materials makes three-dimensional (3D) micro- and nanofabrication available due to efficient confinement of the nonlinear interactions within the focal volume. Additive manufacturing (stereolithography) based on multiphoton absorption (two-photon polymerization) enables the fabrication of 3D polymer micro- and nanostructures for photonic devices, micro- and nanomachines, and microfluidic devices, and has applications for biomedical and tissue engineering. Subtractive manufacturing based on internal modification and fabrication can realize the direct fabrication of 3D microfluidics, micromechanics, microelectronics, and photonic microcomponents in glass. These microcomponents can be easily integrated in a single glass microchip by a simple procedure using a femtosecond laser to realize more functional microdevices, such as optofluidics and integrated photonic microdevices. The highly localized multiphoton absorption of a tightly focused femtosecond laser in glass can also induce strong absorption only at the interface of two closely stacked glass substrates. Consequently, glass bonding can be performed based on fusion welding with femtosecond laser irradiation, which provides the potential for applications in electronics, optics, microelectromechanical systems, medical devices, microfluidic devices, and small satellites. This review paper describes the concepts and principles of femtosecond laser 3D micro- and nanofabrication and presents a comprehensive review on the state-of-the-art, applications, and the future prospects of this technology.
311 citations
TL;DR: Measurements indicate that current X-ray free-electron laser technology should enable structural determination from submicrometre protein crystals with atomic resolution, and the shortest apparent pulse lengths occur at the highest resolution.
Abstract: Researchers describe a mechanism capable of compressing fast and intense X-ray pulses through the rapid loss of crystalline periodicity. It is hoped that this concept, combined with X-ray free-electron laser technology, will allow scientists to obtain structural information at atomic resolutions.
309 citations
TL;DR: Three-dimensional multiphoton lithography at 520 nm has been used to fabricate polymeric woodpile photonic crystal structures that show stop bands in the near-infrared spectral region.
Abstract: Nanoscale features as small as 65 +/- 5 nm have been formed reproducibly by using 520 nm femtosecond pulsed excitation of a 4,4'-bis(di-n-butylamino)biphenyl chromophore to initiate crosslinking in a triacrylate blend. Dosimetry studies of the photoinduced polymerization were performed on chromophores with sizable two-photon absorption cross-sections at 520 and 730 nm. These studies show that sub-diffraction limited line widths are obtained in both cases with the lines written at 520 nm being smaller. Three-dimensional multiphoton lithography at 520 nm has been used to fabricate polymeric woodpile photonic crystal structures that show stop bands in the near-infrared spectral region.
306 citations