The Experts below are selected from a list of 12327 Experts worldwide ranked by ideXlab platform
Takashige Omatsu - One of the best experts on this subject based on the ideXlab platform.
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Optical Vortex induced forward mass transfer manifestation of helical trajectory of Optical Vortex
arXiv: Optics, 2019Co-Authors: Ryosuke Nakamura, Katsuhiko Miyamoto, Kohei Toyoda, Satoyuki Kawano, Haruki Kawaguchi, Muneaki Iwata, Akihiro Kaneko, Ryo Nagura, Takashige OmatsuAbstract:The orbital angular momentum of an Optical Vortex field is found to twist high viscosity donor material to form a micron-scale 'spin jet'. This unique phenomenon manifests the helical trajectory of the Optical Vortex. Going beyond both the conventional ink jet and laser induced forward mass transfer (LIFT) patterning technologies, it also offers the formation and ejection of a micron-scale 'spin jet' of the donor material even with an ultrahigh viscosity of 4 Pas. This Optical Vortex laser induced forward mass transfer (OV-LIFT) patterning technique will enable the development of next generation printed photonic/electric/spintronic circuits formed of ultrahigh viscosity donor dots containing functional nanoparticles, such as quantum dots, metallic particles and magnetic ferrite particles, with ultrahigh spatial resolution. It can also potentially explore a completely new needleless drug injection.
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octave band tunable Optical Vortex parametric oscillator
Optics Express, 2016Co-Authors: Aizitiaili Abulikemu, Taximaiti Yusufu, Roukuya Mamuti, Shungo Araki, Katsuhiko Miyamoto, Takashige OmatsuAbstract:We developed an octave-band tunable Optical Vortex laser based on a 532 nm Optical Vortex pumped Optical parametric oscillator with a simple linear-cavity configuration by employing cascaded non-critical phase-matching LiB3O5 crystals. The Optical Vortex output was tunable from 735 to 1903 nm. For a pump energy of 9 mJ, an Optical Vortex pulse energy of 0.24-2.36 mJ was obtained, corresponding to an Optical-Optical efficiency of 0.3-26%.
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octave band tunable 0 74 1 89μm Optical Vortex laser
Conference on Lasers and Electro-Optics, 2016Co-Authors: Aizitiaili Abulikemu, Taximaiti Yusufu, Roukuya Mamuti, Katsuhiko Miyamoto, Takashige OmatsuAbstract:We developed an octave-band tunable Optical Vortex laser based on a 0.532-μm Optical Vortex-pumped Optical parametric oscillator with an extended cavity configuration by employing cascaded non-critical phase-matching LiB 3 O 5 crystals. The Optical Vortex output was tuned within a wavelength range of 735nm-1893nm, and a pulse energy of 0.24–2.36 mJ was also achieved.
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picosecond Optical Vortex pulse illumination forms a monocrystalline silicon needle
Scientific Reports, 2016Co-Authors: Fuyuto Takahashi, Ryuji Morita, Katsuhiko Miyamoto, Keisaku Yamane, Hirofumi Hidai, Takashige OmatsuAbstract:The formation of a monocrystalline silicon needle by picosecond Optical Vortex pulse illumination was demonstrated for the first time in this study. The dynamics of this silicon needle formation was further revealed by employing an ultrahigh-speed camera. The melted silicon was collected through picosecond pulse deposition to the dark core of the Optical Vortex, forming the silicon needle on a submicrosecond time scale. The needle was composed of monocrystalline silicon with the same lattice index (100) as that of the silicon substrate and had a height of approximately 14 μm and a thickness of approximately 3 μm. Overlaid Vortex pulses allowed the needle to be shaped with a height of approximately 40 μm without any changes to the crystalline properties. Such a monocrystalline silicon needle can be applied to devices in many fields, such as core–shell structures for silicon photonics and photovoltaic devices as well as nano- or microelectromechanical systems.
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tunable 2 μm Optical Vortex parametric oscillator
Optics Express, 2012Co-Authors: Taximaiti Yusufu, Katsuhiko Miyamoto, Yu Tokizane, Masaki Yamada, Takashige OmatsuAbstract:We generated tunable 2-μm Optical Vortex pulses with a topological charge of 1 or 2 in the wavelength range 1.953–2.158 μm by realizing anisotropic transfer of the topological charge from the pump beam to the signal output in a Vortex-pumped half-symmetric Optical parametric oscillator. A maximum Vortex output energy of 2.1 mJ was obtained at a pump energy of 22.8 mJ, which corresponds to a slope efficiency of 15%. The topological charges of the signal and idler output were investigated using a shearing interferometric technique employing a low-spatial-frequency transmission grating.
S. Amoruso - One of the best experts on this subject based on the ideXlab platform.
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Femtosecond laser surface structuring of silicon with Gaussian and Optical Vortex beams
Applied Surface Science, 2017Co-Authors: Jijil Jj Nivas, Domenico Paparo, Shutong He, A. Rubano, Antonio Vecchione, Rosalia Bruzzese, Zhenming Song, Lorenzo Marrucci, S. AmorusoAbstract:We report an experimental analysis of femtosecond laser induced surface structuring of silicon by exploiting both Gaussian and Optical Vortex beams. In particular, we show how different surface patterns, consisting of quasi-periodic ripples and grooves, can be obtained by using different states of polarization offered by Optical Vortex beams. Both for Gaussian and Optical Vortex beams, an increase of the number of laser pulses, N, or beam energy, E0, leads to a progressive predominance of the grooves coverage, with ripples confined in specific regions of the irradiated area at lower fluence. The average period of ripples and grooves shows a different dependence as a function of both E0and N, underlying important differences in mechanisms leading to the formation of ripples and grooves. In particular, our experimental characterization allows identifying a preliminary stage of grooves generation with rudimental surface structures, preferentially directed parallel to the laser polarization. This supports the idea that one possible mechanism of grooves formation lies in the progressive aggregation of clusters of nanoparticles densely decorating the ripples. Our experimental findings provide important indications on the basic understanding of the processes involved in laser surface structuring with ultrashort pulses that can guide the design of the surface patterns.
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direct femtosecond laser surface structuring with Optical Vortex beams generated by a q plate
Scientific Reports, 2015Co-Authors: Jijil Jj Nivas, Domenico Paparo, Shutong He, A. Rubano, Antonio Vecchione, Rosalia Bruzzese, Lorenzo Marrucci, S. AmorusoAbstract:Creation of patterns and structures on surfaces at the micro- and nano-scale is a field of growing interest. Direct femtosecond laser surface structuring with a Gaussian-like beam intensity profile has already distinguished itself as a versatile method to fabricate surface structures on metals and semiconductors. Here we present an approach for direct femtosecond laser surface structuring based on Optical Vortex beams with different spatial distributions of the state of polarization, which are easily generated by means of a q-plate. The different states of an Optical Vortex beam carrying an orbital angular momentum l = ±1 are used to demonstrate the fabrication of various regular surface patterns on silicon. The spatial features of the regular rippled and grooved surface structures are correlated with the state of polarization of the Optical Vortex beam. Moreover, scattered surface wave theory approach is used to rationalize the dependence of the surface structures on the local state of the laser beam characteristics (polarization and fluence). The present approach can be further extended to fabricate even more complex and unconventional surface structures by exploiting the possibilities offered by femtosecond Optical vector fields.
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direct femtosecond laser ablation of copper with an Optical Vortex beam
Journal of Applied Physics, 2014Co-Authors: K. K. Anoop, Rosalba Fittipaldi, A. Rubano, Lorenzo Marrucci, Xuewen Wang, D Paparo, A Vecchione, R Bruzzese, S. AmorusoAbstract:Laser surface structuring of copper is induced by laser ablation with a femtosecond Optical Vortex beam generated via spin-to-orbital conversion of the angular momentum of light by using a q-plate. The variation of the produced surface structures is studied as a function of the number of pulses, N, and laser fluence, F. After the first laser pulse (N = 1), the irradiated surface presents an annular region characterized by a corrugated morphology made by a rather complex network of nanometer-scale ridges, wrinkles, pores, and cavities. Increasing the number of pulses (2 1000) and a deep crater is formed. The nanostructure variation with the laser fluence, F, also evidences an interesting dependence, with a coarsening of the structure morphology as F increases. Our experimental findings demonstrate that direct femtosecond laser ablation with Optical Vortex beams produces interesting patterns not achievable by the more standard beams with a Gaussian intensity profile. They also suggest that appropriate tuning of the experimental conditions (F, N) can allow generating micro- and/or nano-structured surface for any specific application.
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femtosecond laser surface structuring of silicon using Optical Vortex beams generated by a q plate
Applied Physics Letters, 2014Co-Authors: K. K. Anoop, Rosalba Fittipaldi, Domenico Paparo, A. Rubano, Antonio Vecchione, Rosalia Bruzzese, Lorenzo Marrucci, Xuewen Wang, S. AmorusoAbstract:We report on laser surface structuring of silicon using Ti:Sa femtosecond laser ablation with Optical Vortex beams. A q-plate is used to generate an Optical Vortex beam with femtosecond pulse duration through spin-to-orbital conversion of the angular momentum of light. The variation of the produced surface structures is investigated as a function of the number of pulses, N, at laser fluence slightly above the ablation threshold value. At low N (≈10), only surface corrugation of the irradiated, ring-shaped area is observed. This is followed by a progressive formation of regular ripples at larger N (≈100–500), which eventually transform in smaller columnar structures for N ≈ 1000. Moreover, the central, non-ablated part is gradually decorated by nanoparticles produced during laser ablation, a process which eventually leads to the formation of a central turret of assembled nanoparticles. Our experimental findings suggest the importance of a feedback mechanism and a cumulative effect on the formation of ripples with interesting patterns not achievable by the more standard beams with a Gaussian intensity profile.
Grover A Swartzlander - One of the best experts on this subject based on the ideXlab platform.
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sub rayleigh Optical Vortex coronagraphy
Optics Express, 2012Co-Authors: Elettra Mari, Grover A Swartzlander, Fabrizio Tamburini, A Bianchini, C Barbieri, Filippo Romanato, B ThideAbstract:We introduce a new Optical Vortex coronagraph(OVC) method to determine the angular distance between two sources when the separation is sub-Rayleigh. We have found a direct relationship between the position of the minima and the source angular separation. A priori knowledge about the location of the two sources is not required. The superresolution capabilities of an OVC, equipped with an l = 2 N-step spiral phase plate in its Optical path, were investigated numerically. The results of these investigations show that a fraction of the light, increasing with N, from the secondary source can be detected with a sub-Rayleigh resolution of at least 0.1 λ/D.
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the Optical Vortex coronagraph
Journal of Optics, 2009Co-Authors: Grover A SwartzlanderAbstract:An Optical Vortex coronagraph is a high contrast imaging system which has the potential to completely extinguish light from an on-axis point source, allowing glare-free, high throughput imaging of off-axis targets. An important application is the direct detection of exoplanets orbiting distant stars. The Optical physics of the OVC is reviewed, a heuristic argument describing its operation is presented for the first time, and performance limitations are explored.
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astronomical demonstration of an Optical Vortex coronagraph
Optics Express, 2008Co-Authors: Grover A Swartzlander, Erin L Ford, Rukiah S Abdulmalik, Laird M Close, Mary Anne Peters, David Palacios, Daniel W WilsonAbstract:Using an Optical Vortex coronagraph and simple adaptive optics techniques, we have made the first convincing demonstration of an Optical Vortex coronagraph that is coupled to a star gazing telescope. We suppressed by 97% the primary star of a resolvable binary system, Cor Caroli. The stars had an angular separation of 1.9λ/D at our imaging camera. The secondary star suffered no suppression from the Vortex lens.
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observed scattering into a dark Optical Vortex core
Physical Review Letters, 2002Co-Authors: David Palacios, David Rozas, Grover A SwartzlanderAbstract:The dark core of an Optical Vortex was used to detect on-axis, forward-scattered light from a colloidal solution in the single and multiple scattering regimes. Using no adjustable parameters we obtain good agreement with a concentration-dependent scattering model.
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simultaneous trapping of low index and high index microparticles observed with an Optical Vortex trap
Journal of The Optical Society of America B-optical Physics, 1999Co-Authors: K T Gahagan, Grover A SwartzlanderAbstract:We report the first observation of the simultaneous three-dimensional confinement of both a low-index particle and a high-index particle within a single-beam Optical trap by using a strongly focused laser beam containing an Optical Vortex. Experimental and theoretical investigations of the trap stability are described.
Ryuji Morita - One of the best experts on this subject based on the ideXlab platform.
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picosecond Optical Vortex pulse illumination forms a monocrystalline silicon needle
Scientific Reports, 2016Co-Authors: Fuyuto Takahashi, Ryuji Morita, Katsuhiko Miyamoto, Keisaku Yamane, Hirofumi Hidai, Takashige OmatsuAbstract:The formation of a monocrystalline silicon needle by picosecond Optical Vortex pulse illumination was demonstrated for the first time in this study. The dynamics of this silicon needle formation was further revealed by employing an ultrahigh-speed camera. The melted silicon was collected through picosecond pulse deposition to the dark core of the Optical Vortex, forming the silicon needle on a submicrosecond time scale. The needle was composed of monocrystalline silicon with the same lattice index (100) as that of the silicon substrate and had a height of approximately 14 μm and a thickness of approximately 3 μm. Overlaid Vortex pulses allowed the needle to be shaped with a height of approximately 40 μm without any changes to the crystalline properties. Such a monocrystalline silicon needle can be applied to devices in many fields, such as core–shell structures for silicon photonics and photovoltaic devices as well as nano- or microelectromechanical systems.
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ultrashort Optical Vortex pulse generation in few cycle regime
Optics Express, 2012Co-Authors: Keisaku Yamane, Yasunori Toda, Ryuji MoritaAbstract:We generated a 2.3-cycle, 5.9-fs, 56-μJ ultrashort Optical-Vortex pulse (ranging from ∼650 to ∼950 nm) in few-cycle regime, by Optical parametric amplification. It was performed even by using passive elements (a pair of prisms and chirped mirrors) for chirp compensation. Spectrally-resolved interferograms and intensity profiles showed that the obtained pulses have no spatial or topological-charge dispersion during the amplification process. To the best of our knowledge, it is the first generation of Optical-Vortex pulses in few-cycle regime. They can be powerful tools for ultrabroadband and/or ultrafast spectroscopy and experiments of high-intensity field physics.
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using Optical Vortex to control the chirality of twisted metal nanostructures
Nano Letters, 2012Co-Authors: Kohei Toyoda, Ryuji Morita, Katsuhiko Miyamoto, N Aoki, Takashige OmatsuAbstract:We discovered for the first time that light can twist metal to control the chirality of metal nanostructures (hereafter, chiral metal nanoneedles). The helicity of Optical vortices is transferred to the constituent elements of the irradiated material (mostly melted material), resulting in the formation of chiral metal nanoneedles. The chirality of these nanoneedles could be controlled by just changing the sign of the helicity of the Optical Vortex. The tip curvature of these chiral nanoneedles was measured to be <40 nm, which is less than 1/25th of the laser wavelength (1064 nm). Such chiral metal nanoneedles will enable us to selectively distinguish the chirality and Optical activity of molecules and chemical composites on a nanoscale and they will provide chiral selectivity for nanoscale imaging systems (e.g., atomic force microscopes), chemical reactions on plasmonic nanostructures, and planar metamaterials.
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Optical-Vortex laser ablation
Optics Express, 2010Co-Authors: Junichi Hamazaki, Keisuke Chujo, Ryuji Morita, Satoshi Tanda, Yusuke Kobayashi, Takashige OmatsuAbstract:Laser ablation of Ta plates using nanosecond Optical Vortex pulses was carried out, for the first time. It was suggested that owing to orbital angular momentum of Optical Vortex, clearer and smoother processed surfaces were obtained with less ablation threshold fluence, in comparison with the ablation by a nonVortex annular beam modified from a spatially Gaussian beam.
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supercontinuum Optical Vortex pulse generation without spatial or topological charge dispersion
Optics Express, 2009Co-Authors: Yu Tokizane, Ryuji MoritaAbstract:A new achromatic method to generate the Optical Vortex was proposed and supercontinuum Optical Vortex generation ranging ~500 to ~800 nm was experimentally demonstrated without spatial nor topological-charge dispersions. In addition, polarization evolution in our system using Jones vectors and matrices was discussed and the condition of the polarizer to transfer polarizations was elucidated. This method is useful for the application to time-resolved nonlinear spectroscopy utilizing ultrabroadband Optical Vortex pulses in topological materials such as ring-shaped crystals or annular materials.
Lorenzo Marrucci - One of the best experts on this subject based on the ideXlab platform.
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Femtosecond laser surface structuring of silicon with Gaussian and Optical Vortex beams
Applied Surface Science, 2017Co-Authors: Jijil Jj Nivas, Domenico Paparo, Shutong He, A. Rubano, Antonio Vecchione, Rosalia Bruzzese, Zhenming Song, Lorenzo Marrucci, S. AmorusoAbstract:We report an experimental analysis of femtosecond laser induced surface structuring of silicon by exploiting both Gaussian and Optical Vortex beams. In particular, we show how different surface patterns, consisting of quasi-periodic ripples and grooves, can be obtained by using different states of polarization offered by Optical Vortex beams. Both for Gaussian and Optical Vortex beams, an increase of the number of laser pulses, N, or beam energy, E0, leads to a progressive predominance of the grooves coverage, with ripples confined in specific regions of the irradiated area at lower fluence. The average period of ripples and grooves shows a different dependence as a function of both E0and N, underlying important differences in mechanisms leading to the formation of ripples and grooves. In particular, our experimental characterization allows identifying a preliminary stage of grooves generation with rudimental surface structures, preferentially directed parallel to the laser polarization. This supports the idea that one possible mechanism of grooves formation lies in the progressive aggregation of clusters of nanoparticles densely decorating the ripples. Our experimental findings provide important indications on the basic understanding of the processes involved in laser surface structuring with ultrashort pulses that can guide the design of the surface patterns.
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direct femtosecond laser surface structuring with Optical Vortex beams generated by a q plate
Scientific Reports, 2015Co-Authors: Jijil Jj Nivas, Domenico Paparo, Shutong He, A. Rubano, Antonio Vecchione, Rosalia Bruzzese, Lorenzo Marrucci, S. AmorusoAbstract:Creation of patterns and structures on surfaces at the micro- and nano-scale is a field of growing interest. Direct femtosecond laser surface structuring with a Gaussian-like beam intensity profile has already distinguished itself as a versatile method to fabricate surface structures on metals and semiconductors. Here we present an approach for direct femtosecond laser surface structuring based on Optical Vortex beams with different spatial distributions of the state of polarization, which are easily generated by means of a q-plate. The different states of an Optical Vortex beam carrying an orbital angular momentum l = ±1 are used to demonstrate the fabrication of various regular surface patterns on silicon. The spatial features of the regular rippled and grooved surface structures are correlated with the state of polarization of the Optical Vortex beam. Moreover, scattered surface wave theory approach is used to rationalize the dependence of the surface structures on the local state of the laser beam characteristics (polarization and fluence). The present approach can be further extended to fabricate even more complex and unconventional surface structures by exploiting the possibilities offered by femtosecond Optical vector fields.
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direct femtosecond laser ablation of copper with an Optical Vortex beam
Journal of Applied Physics, 2014Co-Authors: K. K. Anoop, Rosalba Fittipaldi, A. Rubano, Lorenzo Marrucci, Xuewen Wang, D Paparo, A Vecchione, R Bruzzese, S. AmorusoAbstract:Laser surface structuring of copper is induced by laser ablation with a femtosecond Optical Vortex beam generated via spin-to-orbital conversion of the angular momentum of light by using a q-plate. The variation of the produced surface structures is studied as a function of the number of pulses, N, and laser fluence, F. After the first laser pulse (N = 1), the irradiated surface presents an annular region characterized by a corrugated morphology made by a rather complex network of nanometer-scale ridges, wrinkles, pores, and cavities. Increasing the number of pulses (2 1000) and a deep crater is formed. The nanostructure variation with the laser fluence, F, also evidences an interesting dependence, with a coarsening of the structure morphology as F increases. Our experimental findings demonstrate that direct femtosecond laser ablation with Optical Vortex beams produces interesting patterns not achievable by the more standard beams with a Gaussian intensity profile. They also suggest that appropriate tuning of the experimental conditions (F, N) can allow generating micro- and/or nano-structured surface for any specific application.
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femtosecond laser surface structuring of silicon using Optical Vortex beams generated by a q plate
Applied Physics Letters, 2014Co-Authors: K. K. Anoop, Rosalba Fittipaldi, Domenico Paparo, A. Rubano, Antonio Vecchione, Rosalia Bruzzese, Lorenzo Marrucci, Xuewen Wang, S. AmorusoAbstract:We report on laser surface structuring of silicon using Ti:Sa femtosecond laser ablation with Optical Vortex beams. A q-plate is used to generate an Optical Vortex beam with femtosecond pulse duration through spin-to-orbital conversion of the angular momentum of light. The variation of the produced surface structures is investigated as a function of the number of pulses, N, at laser fluence slightly above the ablation threshold value. At low N (≈10), only surface corrugation of the irradiated, ring-shaped area is observed. This is followed by a progressive formation of regular ripples at larger N (≈100–500), which eventually transform in smaller columnar structures for N ≈ 1000. Moreover, the central, non-ablated part is gradually decorated by nanoparticles produced during laser ablation, a process which eventually leads to the formation of a central turret of assembled nanoparticles. Our experimental findings suggest the importance of a feedback mechanism and a cumulative effect on the formation of ripples with interesting patterns not achievable by the more standard beams with a Gaussian intensity profile.