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The nanostructuring of transparent media with ultrashort laser pulses has attracted interest due to its unique applications. However, little is understood with respect to the physical mechanisms responsible for the peculiarities of the dielectrics inscribing with high intensity laser beams. It has been shown that spatio-temporal couplings (STC) inherent to the ultrashort pulses make inscribing sensitive...
Optical rectification of ultrashort laser pulses in electro-optic crystals is an established technique of terahertz generation. In this technique, the pump optical pulse produces a nonlinear polarization that moves with the group velocity of the optical pulse and acts as a source of terahertz radiation. The up-to-date generation schemes based on this principle utilize both the standard collinear phase...
The Laser-Induced Forward Transfer (LIFT) process consists of the irradiation, using a pulsed laser, of a thin film (the donor) deposited onto a transparent substrate to induce the ejection of a small part of the irradiated volume and its deposition on a receiver substrate set in close proximity. This simple technology has been widely investigated to print, with high spatial resolution, a wide range...
Optical imaging through complex media such as biological tissue or white paint remains a daily challenge as spatial information gets mixed because of multiple scattering. Without any ballistic light, common microscopy techniques become useless. Over the last decade, spatial light modulators (SLM) have become the indispensable tool to overcome scattering thanks to their millions of degrees of freedom...
The precise characterization of femtosecond laser pulses is as challenging as their generation and a topic of intense research. Dispersion-scan (d-scan) [1] is a recently established technique where the spectrum of a nonlinear signal, e.g., second-harmonic generation (SHG), is measured as a function of dispersion applied to the pulse. The spectral phase of the pulse can then be retrieved from the...
Ultrashort pulse laser ablation is a useful tool in material processing and biomedical fields [1]. A key challenge to expanding the applications of laser ablation is delivering high peak power, ultrashort laser pulses beyond the reach of conventional microscope objectives. Optical fiber endoscopes are widely used to guide light in confined spaces. However, the endoscopic delivery of a focused ultrashort...
A superposition of two optical vortices with different topological charges forms a light wave with azimuthally periodic structure. The beam with such rotational symmetry is called a ring-shaped optical lattice [1]. One of its important features is that it can be flexibly rotated by controlling relative phase difference between them without changing its structure, which offers us rotational degree...
The goal of any pulse characterization protocol is to describe how the spectral components of the electric field are changing in time. Apart from linear methods such as streak cameras, characterization techniques based on nonlinear processes have been developed. Those processes require broad spectral acceptance bandwidths, i.e. to be capable of resolving ultrashort features of the pulse. For many...
A novel nonlinear phenomenon at normal dispersion regime inside of graded-index multimode fiber (GRIN MMF), geometric parametric instability (GPI), can be observed while propagating beam experiences spatio-temporal evolution. Longhi theoretically predicted this GPI and associated with periodic refocusing inside GRIN MMF [1]. Later his work is verified by Krupa et al. [2] and Lopez-Galmiche et al....
An increasing number of scientific applications require highly energetic ultrafast laser system like OPA pumping, THz generation or filamentation. To address their requirements, Amplitude Systems is developing a versatile femtosecond laser system based on diode-pumped Ytterbium doped crystals at ambient temperature. An output energy of 74 mJ at 100 Hz was obtained with a pulse duration as short as...
The generation of ultrashort wavepackets with optical angular momentum (OAM) enables to combine the extreme intensity, temporal localization and spectral bandwidth of pulsed light fields with topological charges. Because of additional rotational degrees of freedom, such potential applications in optical communication, optical tweezing, microscopy, or material modification, pulses with are currently...
Ultrashort laser pulses have shown a huge potential for precise microstructuring. Apart from processing metallic samples [1], especially the possibility to realize three-dimensionally localized modifications within the bulk of transparent materials has gained significant interest. When intense ultrashort pulses are tightly focused into the transparent material, the intensity in the focal volume can...
The controlled energy deposition by nonlinear absorption of ultrashort laser pulses offers a variety of different processing strategies for the machining of wide-bandgap materials. Considering laser-glass cutting applications, efficient single pass processes with volume modifications along the entire substrate thickness become possible using adapted focal field distributions [1]. The required extreme...
Ultrashort pulse fiber lasers (FLs) are required to have higher power to achieve high quality laser processing of difficult-to-cut materials such as carbon fiber reinforced plastics (CFRPs). Our present work develops an all-fiber coherent addition system to achieve a high power ultrashort pulse FL beyond pulse-power limits due to nonlinear effects in rare-earth-doped fiber [1]. Coherent addition is...
Parallel to the rising of a number of scientific and industrial applications of ultrashort laser pulses, their precise temporal characterization has become a major issue. Recently, the new pulse measurement technique of dispersion-scan (d-scan) was introduced, which is based on measuring the spectrum of a nonlinear signal as a function of varying amounts of known dispersion added to the pulse [1]...
Being capable of light localization in the large air-filled core, microstructured hollow-core fibers (HCF) are highly promising for a long-distance high-power ultra-short pulse (USP) delivery due to extremely low fiber nonlinearity. Among them negative-curvature revolver hollow-core fiber (RHCF) having a cladding formed with a single layer of non-touched cylindrical silica glass capillaries [1] is...
Recently reported optical pulse generators may suffer from large pedestal, large duty cycle, bias drift and/or high-power consumption [1, 2]. Besides, each injected CW laser merely results in pulse on one wavelength using these schemes, which is uneconomical. In this study, we propose a multi-wavelength pedestal-free Gaussian optical pulse generator with low duty cycles on wavelengths twice the number...
In the low-frequency THz range optical rectification (OR) in LiNbOs (LN) has been providing the highest THz pulse energies, but limitations became apparent [I]. The potential of semiconductor nonlinear optical materials for high-energy high-field THz pulse generation by OR has been recently demonstrated [2-4]. Whereas pumping OR in ZnTe at 0.8 μm, near its collinear phase-matching wavelength, resulted...
Self-focusing and filamentation of ultrashort mid-infrared laser pulses, whose wavelengths fall in the anomalous group velocity dispersion range of dielectric media, produces supercontinuum radiation with unprecedented spectral coverage [1, 2]. Under such conditions, a qualitatively new filamentation regime is accessed, where simultaneous compression in space and time leads to formation of quasi-stationary...
Spectral broadening techniques based on fibers are prone to damage and are sensitive to alignment, especially when high average (>50 W) and high peak powers (>10 MW) are combined. Broadening techniques in bulk material [1, 2] represent an alternative approach. However, until recently these techniques were limited in efficiency, beam quality and bandwidth. A lately demonstrated concept of multipass...
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