The Experts below are selected from a list of 15210 Experts worldwide ranked by ideXlab platform
Katerina E Aifantis - One of the best experts on this subject based on the ideXlab platform.
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thermoplastic deformation of silicon surfaces induced by ultrashort Pulsed Lasers in submelting conditions
Journal of Applied Physics, 2012Co-Authors: George D. Tsibidis, Emmanuel Stratakis, Katerina E AifantisAbstract:A hybrid theoretical model is presented to describe thermoplastic deformation effects on silicon surfaces induced by single and multiple ultrashort Pulsed laser irradiation in submelting conditions. An approximation of the Boltzmann transport equation is adopted to describe the laser irradiation process. The evolution of the induced deformation field is described initially by adopting the differential equations of dynamic thermoelasticity while the onset of plastic yielding is described by the von Mises stress. Details of the resulting picometre sized crater, produced by irradiation with a single pulse, are discussed as a function of the imposed conditions and thresholds for the onset of plasticity are computed. Irradiation with multiple pulses leads to ripple formation of nanometre size that originates from the interference of the incident and a surface scattered wave. It is suggested that ultrafast laser induced surface modification in semiconductors is feasible in submelting conditions, and it may act ...
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thermoplastic deformation of silicon surfaces induced by ultrashort Pulsed Lasers in submelting conditions
Journal of Applied Physics, 2012Co-Authors: George D. Tsibidis, Emmanuel Stratakis, Katerina E AifantisAbstract:A hybrid theoretical model is presented to describe thermoplastic deformation effects on silicon surfaces induced by single and multiple ultrashort Pulsed laser irradiation in submelting conditions. An approximation of the Boltzmann transport equation is adopted to describe the laser irradiation process. The evolution of the induced deformation field is described initially by adopting the differential equations of dynamic thermoelasticity while the onset of plastic yielding is described by the von Mises stress. Details of the resulting picometre sized crater, produced by irradiation with a single pulse, are discussed as a function of the imposed conditions and thresholds for the onset of plasticity are computed. Irradiation with multiple pulses leads to ripple formation of nanometre size that originates from the interference of the incident and a surface scattered wave. It is suggested that ultrafast laser induced surface modification in semiconductors is feasible in submelting conditions, and it may act as a precursor of the incubation effects observed at multiple pulse irradiation of materials surfaces.
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thermoplastic deformation of silicon surfaces induced by ultrashort Pulsed Lasers in submelting conditions
arXiv: Materials Science, 2011Co-Authors: George D. Tsibidis, Emmanuel Stratakis, Katerina E AifantisAbstract:A hybrid 2D theoretical model is presented to describe thermoplastic deformation effects on silicon surfaces induced by single and multiple ultrashort Pulsed laser irradiation in submelting conditions. An approximation of the Boltzmann transport equation is adopted to describe the laser irradiation process. The evolution of the induced deformation field is described initially by adopting the differential equations of dynamic thermoelasticity while the onset of plastic yielding is described by the von Mise's stress. Details of the resulting picometre sized crater, produced by irradiation with a single pulse, are then discussed as a function of the imposed conditions and thresholds for the onset of plasticity are computed. Irradiation with multiple pulses leads to ripple formation of nanometre size that originates from the interference of the incident and a surface scattered wave. It is suggested that ultrafast laser induced surface modification in semiconductors is feasible in submelting conditions, and it may act as a precursor of the incubation effects observed at multiple pulse irradiation of materials surfaces.
George D. Tsibidis - One of the best experts on this subject based on the ideXlab platform.
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Convection roll-driven generation of supra-wavelength periodic surface structures on dielectrics upon irradiation with femtosecond Pulsed Lasers
Physical Review B, 2016Co-Authors: George D. Tsibidis, Evangelos Skoulas, Antonis Papadopoulos, Emmanuel StratakisAbstract:The significance of the magnitude of the Prandtl number of a fluid in the propagation direction of induced convection rolls is elucidated. Specifically, we report on the physical mechanism to account for the formation and orientation of previously unexplored supra-wavelength periodic surface structures in dielectrics, following melting and subsequent capillary effects induced upon irradiation with ultrashort laser pulses. Counterintuitively, it is found that such structures exhibit periodicities, which are markedly, even multiple times, higher than the laser excitation wavelength. It turns out that the extent to which the hydrothermal waves relax depends upon the laser beam energy, produced electron densities upon excitation with femtosecond Pulsed Lasers, the magnitude of the induced initial local roll disturbances, and the magnitude of the Prandtl number with direct consequences on the orientation and size of the induced structures. It is envisaged that this elucidation may be useful for the interpretation of similar, albeit large-scale periodic or quasiperiodic structures formed in other natural systems due to thermal gradients, while it can also be of great importance for potential applications in biomimetics.
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thermoplastic deformation of silicon surfaces induced by ultrashort Pulsed Lasers in submelting conditions
Journal of Applied Physics, 2012Co-Authors: George D. Tsibidis, Emmanuel Stratakis, Katerina E AifantisAbstract:A hybrid theoretical model is presented to describe thermoplastic deformation effects on silicon surfaces induced by single and multiple ultrashort Pulsed laser irradiation in submelting conditions. An approximation of the Boltzmann transport equation is adopted to describe the laser irradiation process. The evolution of the induced deformation field is described initially by adopting the differential equations of dynamic thermoelasticity while the onset of plastic yielding is described by the von Mises stress. Details of the resulting picometre sized crater, produced by irradiation with a single pulse, are discussed as a function of the imposed conditions and thresholds for the onset of plasticity are computed. Irradiation with multiple pulses leads to ripple formation of nanometre size that originates from the interference of the incident and a surface scattered wave. It is suggested that ultrafast laser induced surface modification in semiconductors is feasible in submelting conditions, and it may act ...
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thermoplastic deformation of silicon surfaces induced by ultrashort Pulsed Lasers in submelting conditions
Journal of Applied Physics, 2012Co-Authors: George D. Tsibidis, Emmanuel Stratakis, Katerina E AifantisAbstract:A hybrid theoretical model is presented to describe thermoplastic deformation effects on silicon surfaces induced by single and multiple ultrashort Pulsed laser irradiation in submelting conditions. An approximation of the Boltzmann transport equation is adopted to describe the laser irradiation process. The evolution of the induced deformation field is described initially by adopting the differential equations of dynamic thermoelasticity while the onset of plastic yielding is described by the von Mises stress. Details of the resulting picometre sized crater, produced by irradiation with a single pulse, are discussed as a function of the imposed conditions and thresholds for the onset of plasticity are computed. Irradiation with multiple pulses leads to ripple formation of nanometre size that originates from the interference of the incident and a surface scattered wave. It is suggested that ultrafast laser induced surface modification in semiconductors is feasible in submelting conditions, and it may act as a precursor of the incubation effects observed at multiple pulse irradiation of materials surfaces.
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thermoplastic deformation of silicon surfaces induced by ultrashort Pulsed Lasers in submelting conditions
arXiv: Materials Science, 2011Co-Authors: George D. Tsibidis, Emmanuel Stratakis, Katerina E AifantisAbstract:A hybrid 2D theoretical model is presented to describe thermoplastic deformation effects on silicon surfaces induced by single and multiple ultrashort Pulsed laser irradiation in submelting conditions. An approximation of the Boltzmann transport equation is adopted to describe the laser irradiation process. The evolution of the induced deformation field is described initially by adopting the differential equations of dynamic thermoelasticity while the onset of plastic yielding is described by the von Mise's stress. Details of the resulting picometre sized crater, produced by irradiation with a single pulse, are then discussed as a function of the imposed conditions and thresholds for the onset of plasticity are computed. Irradiation with multiple pulses leads to ripple formation of nanometre size that originates from the interference of the incident and a surface scattered wave. It is suggested that ultrafast laser induced surface modification in semiconductors is feasible in submelting conditions, and it may act as a precursor of the incubation effects observed at multiple pulse irradiation of materials surfaces.
Emmanuel Stratakis - One of the best experts on this subject based on the ideXlab platform.
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Convection roll-driven generation of supra-wavelength periodic surface structures on dielectrics upon irradiation with femtosecond Pulsed Lasers
Physical Review B, 2016Co-Authors: George D. Tsibidis, Evangelos Skoulas, Antonis Papadopoulos, Emmanuel StratakisAbstract:The significance of the magnitude of the Prandtl number of a fluid in the propagation direction of induced convection rolls is elucidated. Specifically, we report on the physical mechanism to account for the formation and orientation of previously unexplored supra-wavelength periodic surface structures in dielectrics, following melting and subsequent capillary effects induced upon irradiation with ultrashort laser pulses. Counterintuitively, it is found that such structures exhibit periodicities, which are markedly, even multiple times, higher than the laser excitation wavelength. It turns out that the extent to which the hydrothermal waves relax depends upon the laser beam energy, produced electron densities upon excitation with femtosecond Pulsed Lasers, the magnitude of the induced initial local roll disturbances, and the magnitude of the Prandtl number with direct consequences on the orientation and size of the induced structures. It is envisaged that this elucidation may be useful for the interpretation of similar, albeit large-scale periodic or quasiperiodic structures formed in other natural systems due to thermal gradients, while it can also be of great importance for potential applications in biomimetics.
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thermoplastic deformation of silicon surfaces induced by ultrashort Pulsed Lasers in submelting conditions
Journal of Applied Physics, 2012Co-Authors: George D. Tsibidis, Emmanuel Stratakis, Katerina E AifantisAbstract:A hybrid theoretical model is presented to describe thermoplastic deformation effects on silicon surfaces induced by single and multiple ultrashort Pulsed laser irradiation in submelting conditions. An approximation of the Boltzmann transport equation is adopted to describe the laser irradiation process. The evolution of the induced deformation field is described initially by adopting the differential equations of dynamic thermoelasticity while the onset of plastic yielding is described by the von Mises stress. Details of the resulting picometre sized crater, produced by irradiation with a single pulse, are discussed as a function of the imposed conditions and thresholds for the onset of plasticity are computed. Irradiation with multiple pulses leads to ripple formation of nanometre size that originates from the interference of the incident and a surface scattered wave. It is suggested that ultrafast laser induced surface modification in semiconductors is feasible in submelting conditions, and it may act ...
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thermoplastic deformation of silicon surfaces induced by ultrashort Pulsed Lasers in submelting conditions
Journal of Applied Physics, 2012Co-Authors: George D. Tsibidis, Emmanuel Stratakis, Katerina E AifantisAbstract:A hybrid theoretical model is presented to describe thermoplastic deformation effects on silicon surfaces induced by single and multiple ultrashort Pulsed laser irradiation in submelting conditions. An approximation of the Boltzmann transport equation is adopted to describe the laser irradiation process. The evolution of the induced deformation field is described initially by adopting the differential equations of dynamic thermoelasticity while the onset of plastic yielding is described by the von Mises stress. Details of the resulting picometre sized crater, produced by irradiation with a single pulse, are discussed as a function of the imposed conditions and thresholds for the onset of plasticity are computed. Irradiation with multiple pulses leads to ripple formation of nanometre size that originates from the interference of the incident and a surface scattered wave. It is suggested that ultrafast laser induced surface modification in semiconductors is feasible in submelting conditions, and it may act as a precursor of the incubation effects observed at multiple pulse irradiation of materials surfaces.
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thermoplastic deformation of silicon surfaces induced by ultrashort Pulsed Lasers in submelting conditions
arXiv: Materials Science, 2011Co-Authors: George D. Tsibidis, Emmanuel Stratakis, Katerina E AifantisAbstract:A hybrid 2D theoretical model is presented to describe thermoplastic deformation effects on silicon surfaces induced by single and multiple ultrashort Pulsed laser irradiation in submelting conditions. An approximation of the Boltzmann transport equation is adopted to describe the laser irradiation process. The evolution of the induced deformation field is described initially by adopting the differential equations of dynamic thermoelasticity while the onset of plastic yielding is described by the von Mise's stress. Details of the resulting picometre sized crater, produced by irradiation with a single pulse, are then discussed as a function of the imposed conditions and thresholds for the onset of plasticity are computed. Irradiation with multiple pulses leads to ripple formation of nanometre size that originates from the interference of the incident and a surface scattered wave. It is suggested that ultrafast laser induced surface modification in semiconductors is feasible in submelting conditions, and it may act as a precursor of the incubation effects observed at multiple pulse irradiation of materials surfaces.
Han Zhang - One of the best experts on this subject based on the ideXlab platform.
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Pulsed Lasers employing solution processed plasmonic cu3 x p colloidal nanocrystals
Advanced Materials, 2016Co-Authors: Zeke Liu, Han Zhang, Si Xiao, Rongbin Wang, Zhiteng Wang, Weiwei Wang, Yongjie Wang, Xiangxiang Zhu, Shuittong Lee, Qiaoliang BaoAbstract:A new approach to synthesize self-doped colloidal Cu3-x P NCs with controlled size and localized surface plasmon resonance absorption is reported. These Cu3-x P NCs show ultrafast exciton dynamics and huge optical nonlinearities due to plasmonic resonances, which afford the first demonstration of plasmonic Cu3-x P NCs as simple, effective, and solution-processed nonlinear absorbers for high-energy Q-switched fiber laser.
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black phosphorus polymer composites for Pulsed Lasers
Advanced Optical Materials, 2015Co-Authors: Han Zhang, Shenghuang Lin, Zhongchi Wang, Si Xiao, Yao Chen, Haifeng Bao, Shu Ping Lau, Chunxu Pan, Dianyuan FanAbstract:Black phosphorus (BP) is a very promising material for telecommunication due to its direct bandgap and strong resonant absorption in near-infrared wavelength range. However, ultrafast nonlinear photonic applications relying on the ultrafast photocarrier dynamics as well as optical nonlinearity in black phosphorus remain unexplored. In this work, nonlinear optical properties of solution exfoliated BP are investigated and the usage of BP as a new saturable absorber for high energy pulse generation in fiber laser is demonstrated. In order to avoid the oxidization and degradation, BP is encapsulated by polymer matrix which is optically transparent in the spectrum range of interest to form a composite. Two fabrication approaches are demonstrated to produce BP-polymer composite films which are further incorporated into fiber laser cavity as nonlinear media. BP shows very fast carrier dynamics and BP-polymer composite has a modulation depth of 10.6%. A highly stable Q-switched pulse generation is achieved and the single pulse energy of 194 nJ is demonstrated. The ease of handling of such black phosphorus-polymer composite thin films affords new opportunities for wider applications such as optical sensing, signal processing, and light modulation.
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multilayer black phosphorus as broadband saturable absorber for Pulsed Lasers from 1 to 2 7 mu m wavelength
arXiv: Optics, 2015Co-Authors: Lingchen Kong, Zhipeng Qin, Guoqiang Xie, Zhinan Guo, Han Zhang, Peng Yuan, Liejia QianAbstract:It attracts wide interest to seek universe saturable absorber covering wavelengths from near infrared to mid-infrared band. Multilayer black phosphorus, with variable direct bandgap (0.3-2 eV) depending on the layer number, becomes a good alternative as a universe saturable absorber for Pulsed Lasers. In this contribution, we first experimentally demonstrated broadband saturable absorption of multilayer black phosphorus from 1 {\mu}m to 2.7 {\mu}m wavelength. With the as-fabricated black phosphorus nanoflakes as saturable absorber, stable Q-switching operation of bulk Lasers at 1.03 {\mu}m, 1.93 {\mu}m, 2.72 {\mu}m were realized, respectively. In contrast with large-bandgap semiconducting transition metal dichalcogenides, such as MoS2, MoSe2, multilayer black phosphorus shows particular advantage at the long wavelength regime thanks to its narrow direct bandgap. This work will open promising optoelectronic applications of black phosphorus in mid-infrared spectral region and further demonstrate that BP may fill the gap of between zero-bandgap graphene and large-bandgap TMDs.
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black phosphorus polymer composites for Pulsed Lasers
arXiv: Materials Science, 2015Co-Authors: Han Zhang, Shenghuang Lin, Zhongchi Wang, Si Xiao, Yao Chen, Haifeng Bao, Shu Ping Lau, Chunxu Pan, Dianyuan FanAbstract:Black phosphorus is a very promising material for telecommunication due to its direct bandgap and strong resonant absorption in near-infrared wavelength range. However, ultrafast nonlinear photonic applications relying on the ultrafast photo-carrier dynamics as well as optical nonlinearity in black phosphorus remain unexplored. In this work, we investigate nonlinear optical properties of solution exfoliated BP and demonstrate the usage of BP as a new saturable absorber for high energy pulse generation in fiber laser. In order to avoid the oxidization and degradation of BP, we encapsulated BP by polymer matrix which is optically transparent in the spectrum range of interest to form a composite. Two fabrication approaches were demonstrated to produce BP-polymer composite films which were further incorporated into fiber laser cavity as nonlinear media. BP shows very fast carrier dynamics and BP-polymer composite has a modulation depth of 10.6%. A highly stable Q-switched pulse generation was achieved and the single pulse energy of ~194 nJ was demonstrated. The ease of handling of such black phosphorus-polymer composite thin films affords new opportunities for wider applications such as optical sensing, signal processing and light modulation.
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atomic layer graphene as saturable absorber for ultrafast Pulsed Lasers
arXiv: Optics, 2009Co-Authors: Qiaoliang Bao, Han Zhang, Yu Wang, Yongli Yan, Zexiang Shen, Kian Ping Loh, Dingyuan TangAbstract:The optical conductance of monolayer graphene is defined solely by the fine structure constant. The absorbance has been predicted to be independent of frequency. In principle, the interband optical absorption in zero-gap graphene could be saturated readily under strong excitation due to Pauli blocking. Here, we demonstrate the use of atomic layer graphene as saturable absorber in a mode-locked fiber laser for the generation of ultrashort soliton pulses (756 fs) at the telecommunication band. The modulation depth can be tuned in a wide range from 66.5% to 6.2% by varying the thickness of graphene. Our results suggest that ultrathin graphene films are potentially useful as optical elements in fiber Lasers. Graphene as a laser mode locker can have many merits such as lower saturation intensity, ultrafast recovery time, tunable modulation depth and wideband tuneability.
Yongwon Song - One of the best experts on this subject based on the ideXlab platform.
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deformation immunized optical deposition of graphene for ultrafast Pulsed Lasers
Applied Physics Letters, 2011Co-Authors: Hyungseok Kim, Junhyun Cho, Sungyeon Jang, Yongwon SongAbstract:We demonstrate deformation-suppressed optical deposition of graphene onto an optical fiber by forming a graphene/polyvinyl acetate (PVAc) composite for ultrafast nonlinear photonics. With pure graphene, its nonlinear operation threshold is elevated by the optical deposition that cannot guarantee the intact two-dimensional nanoshape of graphene. The role of PVAc that provides immunity to graphene against deleterious degradation of morphology and optical nonlinearity is elucidated via electron microscope analysis, Raman characterization, and realizing passive mode-locking operation of fiber Lasers. Resultant center wavelength, spectral width, and repetition rate of the laser pulses are 1572.6 nm, 0.6 nm, and 91.5 MHz, respectively.
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carbon nanotube mode lockers with enhanced nonlinearity via evanescent field interaction in d shaped fibers
Optics Letters, 2007Co-Authors: Yongwon Song, Shinji YamashitaAbstract:We demonstrate a novel passive mode-locking scheme for Pulsed Lasers enhanced by the interaction of carbon nanotubes (CNTs) with the evanescent field of propagating light in a D-shaped optical fiber. The scheme features all-fiber operation as well as a long lateral interaction length, which guarantees a strong nonlinear effect from the nanotubes. Mode locking is achieved with less than 30% of the CNTs compared with the amount of nanotubes used for conventional schemes. Our method also ensures the preservation of the original morphology of the individual CNTs. The demonstrated Pulsed laser with our CNT mode locker has a repetition rate of 5.88 MHz and a temporal pulse width of 470 fs.
