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Bessel beams exploit conical energy flow to yield near-uniform intensity along a line focus which has been shown to be extremely attractive for laser processing in dielectrics. At high power, however, the nonlinear Kerr effect is known to induce significant oscillations of the on-axis intensity which is deleterious for machining applications. Here, we show through theory and numerical modelling how...
Recent advances in cavity quantum optomechanics have enabled breakthroughs such as ground state cooling of mechanical motion, observation of quantum backaction, standard quantum limit of position measurement and entanglement between optical and mechanical degrees of freedom [1]. Simultaneously, the upgraded version of current gravitational-wave interferometers is expected to suffer from optomechanical...
We report on the fabrication of highly ordered, multi-directional, complex surface structures that mimic the unique morphological features of certain species found in nature. In particular femtosecond laser pulses with various polarizations states, such as circular and vectorial, were utilized for structuring metal and dielectric surfaces. Experimental results showed that the direction of LIPSS in...
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...
Terahertz (THz) sources are indispensable for various applications such as THz time-domain spectroscopy. A promising approach to generate broadband THz radiation is to employ laser-induced gas plasmas, which has already been demonstrated for various settings [1, 2]. In order to miniaturize such sources, it has been proposed to exploit single-color laser-induced microplasmas [3]. Then, a conical THz...
Currently lasers are perceived as unique light that can produce specific states of matter through selective manipulations that could not be realized using any other conventional incoherent addition of thermal or electronic energy to a system. Although the selective laser chemistry is still a dream, the selective control of material processing done by optimization of laser intensity, as well as the...
Direct UV written planar waveguides in silica have been explored for over two decades [1]. The technique is capable of fabricating low-loss channel waveguides, couplers and Bragg gratings by translating an appropriate substrate through a focused UV beam. To date direct UV written waveguides have been primarily formed by using 244nm laser light, relying on the photosensitivity provided by germanium...
Traditional lasers are composed by three basic elements: an amplifying medium, an external pumping setup, and an optical cavity that confines and shapes the emitted light in well-determined modes and directions. However, several modern approaches are extending this traditional laser paradigm into new avenues. Cavity-free stimulated emission of radiation has been widely studied in random lasers (RLs)...
Mid-infrared coherent sources at 3–4 μm have a wide variety of applications that include, but are not limited to gas sensing, material processing and production control. The MgO-doped periodically poled lithium niobate (MgO:PPLN) crystal is a well-known nonlinear element for quasi-phase-matched optical parametric oscillators (OPOs) typically pumped by 1-μm laser radiation [1]. However, strong multi-phonon...
Label-free optical microscopy plays an important role in biological research. Coherent Raman microscopy combines three-dimensional resolution and fast image acquisition with molecular selectivity based on the vibrational spectrum of the sample. During the last years stimulated Raman scattering (SRS) microscopy has become an important technique in this framework since it does not display an electronic...
Detection of chemical species using differential absorption lidar is a topic of growing interest for safety in petrochemical facilities, outdoor air quality measurements, greenhouse gases monitoring from space, and standoff detection of toxic chemical plumes. In such a lidar the optical source must combine a high energy (> 10 mJ for range-resolved detection), a wide and arbitrary wavelength tunability,...
Fiber and bulk lasers form two distinct classes of solid-state laser, both of which have achieved tremendous success in various arenas, but they are not without their limitations. The long, thin geometry of a fiber allows excellent heat dissipation, which combined with a waveguiding structure provides stronger resilience to thermally-induced mode distortions than in bulk lasers, allowing diffraction-limited...
Optical phenomena in disordered media have attracted a lot of interest over the recent years due to their potential use in a wide range of applications. Beyond the careful understanding of light propagation in these media, potential devices such as random lasers have been proposed with several advantages notably in microscopy. Nonlinear processes can also take advantage of random media. Multiphoton...
Modulation instability (MI) refers to a process where a weak periodic perturbation of an intense continuous wave (CW) grows exponentially as a result of the interplay between dispersion and nonlinearity. In its most basic manifestation, it can be observed in homogeneous optical fibers in the anomalous dispersion regime. Another kind of MI, named parametric instability (PI), is induced by the periodic...
Within recent years many ultra-short pulsed lasers with extremely high pulse energies as well as average powers were developed for laser material processing. To flexibly guide the beam from the laser to the workpiece hollow-core photonic crystal fibers (HC-PCF) have shown to be the best and unique choice to deliver these high peak power pulses. Also it has been reported that to largely reduce the...
A major advantage of solid-state lasers emitting in the 1 μm wavelength range is the possibility of using optical fibers for flexible beam delivery. This is already state of the art in laser material macro-processing with multimode beams. For modern high-brightness lasers with a diffraction-limited beam the guiding is restrained to a few meters or low powers due to nonlinear effects, mainly to Stimulated...
Laser-induced forward transfer appears to be one of the key players of additive manufacturing at the micrometer scale. The basic concept of LIFT consists in the backside laser irradiation of a thin donor film, in solid[1], paste[2] or liquid[3] state, coated on a transparent substrate to transfer a small volume of the donor material onto a receiver substrate placed nearby. From investigations on different...
Sapphire is a transparent crystalline dielectric of high hardness with many important applications, specifically to the next-generation touchscreens and to the LED growth, as substrates. However, sapphire cutting by ablative techniques is rather slow therefore fast material separation techniques are needed. Material separation by “stealth dicing” has been recently developed, it is based on material...
Few-cycle femtosecond pulses (∼10 fs) have proven their interest in highly-controlled interaction with dielectric materials [1]. For efficient single-shot ablation, intensities exceeding 1014 W/cm2 at the target surface are required. However, for such intensities, working in air ambience rapidly yields significant nonlinear spatial distortion of the beam in the pre-focal region, or even air ionization,...
Ultrafast lasers in association to beam shaping have shown to be excellent candidates for transparent material processing [1]. Non-diffractive solutions such as Bessel beams allows for precise energy deposition since they are robust to undesired non-linear effects and as they do not distort along the propagation [2]. This offers important opportunities in laser-assisted cleaving, i.e. mechanical medium...
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