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.
Papers published on a yearly basis
Papers
More filters
TL;DR: In this paper, double-charge femtosecond vortices were synthesized with a polarization-singularity beam converter based on light propagation in a uniaxial anisotropic medium and then focused using moderate and high-NA optics (viz., NA=0.45 and 0.9) to ablate fused silica and soda-lime glass.
Abstract: In this Letter we present the first (to our knowledge) demonstration of material modification using tightly focused single femtosecond laser vortex pulses. Double-charge femtosecond vortices were synthesized with a polarization-singularity beam converter based on light propagation in a uniaxial anisotropic medium and then focused using moderate- and high-NA optics (viz., NA=0.45 and 0.9) to ablate fused silica and soda-lime glass. By controlling the pulse energy, we consistently machine micrometer-size ring-shaped structures with <100nm uniform groove thickness.
162 citations
TL;DR: The results demonstrate that functional crystals can be formed three dimensionally in glasses by use of a nonresonant ultrashort pulsed laser.
Abstract: We report on space-selective growth of a second-harmonic-generation β‐BaB2O4 (BBO) crystal inside a BaO–Al2O3–B2O3 glass sample at the focal point of an 800-nm femtosecond laser beam. A spherical heated region was formed during the focused laser irradiation through observation with an optical microscope. We moved the heated region by changing the position of the focal point of the laser beam relative to the glass sample. We grew BBO crystal continuously in the glass sample by adjusting the moving speed of the heated zone. Our results demonstrate that functional crystals can be formed three dimensionally in glasses by use of a nonresonant ultrashort pulsed laser.
162 citations
TL;DR: In this paper, the authors demonstrate that when the direction of the femtosecond laser beam is reversed from the +z to −z direction, the structures written in LiNbO3 crystal when translating the beam along the +y and −y directions are mirrored.
Abstract: Photosensitivity is a material property that is relevant to many phenomena and applications, from photosynthesis and photography to optical data storage and ultrafast laser writing. It was commonly thought that, in a homogeneous medium, photosensitivity and the corresponding light-induced material modifications do not change on reversing the direction of light propagation. Here we demonstrate that when the direction of the femtosecond laser beam is reversed from the +z to –z direction, the structures written in LiNbO3 crystal when translating the beam along the +y and –y directions are mirrored. In a non-centrosymmetric medium, modification of the material can therefore differ for light propagating in opposite directions. This is the first evidence of a new optical phenomenon of non-reciprocal photosensitivity. We interpret this effect in terms of light pressure and associated heat flow, resulting in a temperature gradient in homogeneous media without inversion symmetry under uniform intense irradiation.
162 citations
TL;DR: M maskless, single-step fabrication of strongly birefringent Fresnel zone plates by focusing of femtosecond laser pulses deep within silica substrates is demonstrated.
Abstract: We demonstrate maskless, single-step fabrication of strongly birefringent Fresnel zone plates by focusing of femtosecond laser pulses deep within silica substrates. The process allows us to produce alternate zone rings directly by inducing a local refractive-index modification of the order of n~10-2 . The embedded zone plates shown in this Letter exhibit efficiencies that vary by as much as a factor of ~6 for orthogonal polarizations. Focal lengths of primary and secondary foci are shown to compare well with theory.
162 citations
TL;DR: The authors' results unambiguously show how initially localized chemical changes can propagate at the level of the global protein conformation in the picosecond timescale.
Abstract: Light absorption can trigger biologically relevant protein conformational changes The light-induced structural rearrangement at the level of a photoexcited chromophore is known to occur in the femtosecond timescale and is expected to propagate through the protein as a quake-like intramolecular motion Here we report direct experimental evidence of such 'proteinquake' observed in myoglobin through femtosecond X-ray solution scattering measurements performed at the Linac Coherent Light Source X-ray free-electron laser An ultrafast increase of myoglobin radius of gyration occurs within 1 picosecond and is followed by a delayed protein expansion As the system approaches equilibrium it undergoes damped oscillations with a ~36-picosecond time period Our results unambiguously show how initially localized chemical changes can propagate at the level of the global protein conformation in the picosecond timescale
162 citations