Magnetic field effect on the self-focusing of an intense laser pulse interacting with a bulk medium of graphite nanoparticles

Javan, N. Sepehri; Erdi, F. Rouhi; Najafi, M. N.

doi:10.1063/1.4981386

Cited by 16 publications

(14 citation statements)

References 39 publications

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“…An identical behavior to [39,40,52] for their investigation on size of nanoparticles has also been obtained in our scheme when height-to-radius ratio of the cylinders is evaluated on the THz field. Moreover, higher efficiency has been obtained in our case as compared to [39,40,[52][53][54]. Overall we can conclude that our results are in agreement with the observations of the other researchers [26,[35][36][37][38][39][40][52][53][54] while the amplitude of the emitted THz radiation and the efficiency in our case is much higher.…”

Section: Resultssupporting

confidence: 92%

“…Moreover, higher efficiency has been obtained in our case as compared to [39,40,[52][53][54]. Overall we can conclude that our results are in agreement with the observations of the other researchers [26,[35][36][37][38][39][40][52][53][54] while the amplitude of the emitted THz radiation and the efficiency in our case is much higher. In addition, our proposal of a medium containing conductive nanocylinders which is illuminated by the hat-top lasers is quite effective based on which we can tune the emitted THz radiation in terms of its frequency, focus and intensity.…”

Section: Resultssupporting

confidence: 92%

“…This finally leads to the enhanced efficiency of the scheme. We have compared our results with the experimental findings of Polyushkin et al [35], Welsh et al [36] and Zhang et al [37], and theoretical studies of Kajikawa et al [38], Sepehri Javan and Rouhi Erdi [39], Sharma et al [40], Varshney et al [52], Thakur et al [53] and Sepehri Javan et al [54] who considered Gaussian, super-Gaussian, top head, ring shaped or hollow Gaussian laser beams for their study. In our case, the host medium having cylindrical graphite nanocylinders is irradiated by the hat-top laser beams.…”

Section: Resultsmentioning

confidence: 82%

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Hat-Top Beams for Generating Tunable THz Radiations Using a Medium of Conducting Nanocylinders

2021

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There are a large number of studies for terahertz (THz) radiation generation, but tunable THz sources are still a challenge since it is difficult to tune frequency, focus and intensity of the radiation simultaneously. The present work proposes the THz generation by the interaction of two hat-top laser beams with a host medium of argon gas containing graphite nanocylinders, as these beams result in highly nonlinear interaction because of a smooth dip in their peak intensity and a fast rise and fall in the overall intensity pattern. Such an interaction produces nonlinear current (6.7 × 108 A/m2) because of the electron cloud of the nanocylinders, which can be modulated by the laser and medium properties for realizing tunable THz radiation. The orientation of basal planes of nanocylinders is shown to be important for this mechanism, though it may be challenging for the experimentalists. The resonant excitation takes place when the plasmon frequency matches the beating frequency of the laser beams, and in the proposed mechanism one can have longitudinal surface plasmon resonance (~12 THz) and transverse surface plasmon resonance (~40 THz), leading to frequency-tunable THz radiation. The role of height and inter particle distance between the adjacent nanocylinders on the THz field amplitude and the efficiency of the mechanism is uncovered by controlling the aspect ratio in the nanocylinders. For example, reducing the inter particle distance from 180 nm to 60 nm leads to the enhancement of THz field from 1 × 108 V/m to 5.48 × 108 V/m. The profile of the emitted THz radiation is investigated in detail under the effect of various parameters in order to prove the practicality of the proposal. The proposed design and mechanism would be attractive for electromagnetic and communication societies which are dealing with millimeter-waves and THz components in addition to its medical application.

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Section: Resultssupporting

confidence: 92%

Section: Resultssupporting

confidence: 92%

Section: Resultsmentioning

confidence: 82%

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Hat-Top Beams for Generating Tunable THz Radiations Using a Medium of Conducting Nanocylinders

2021

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“…All the mentioned facts in this paragraph, may emphasize on the importance of considering restoring force in dynamical problems related to the interaction of EMWs with MNPs in the classical regime. In some studies related to the interaction of EMWs with systems including MNPs, in classical momentum equation, the restoring force which can predict the resonance frequency is considered [54][55][56][57][58][59][60][61][62][63][64][65][66][67] but surprisingly it is absent in the dynamics of the most of the studies related to the Drude-based problems and as it is mentioned in the previous paragraph, they considered only the free path limitation on the dynamics of conduction electrons in MNPs. In some studies related to the plasmonics of metallic nanostructures, for extraction of permittivity of system by Drude-based models, in the equation of motion of damped harmonic oscillation, the restoring force is considered and the related spring constant is determined by simulation [68][69][70][71][72][73].…”

Section: Introductionmentioning

confidence: 99%

Modified Drude model for small gold nanoparticles surface plasmon resonance based on the role of classical confinement

Kheirandish

Javan

Mohammadzadeh

2020

Sci Rep

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In this paper, we study the effect of restoration force caused by the limited size of a small metallic nanoparticle (MNP) on its linear response to the electric field of incident light. In a semiclassical phenomenological Drude-like model for small MNP, we consider restoration force caused by the displacement of conduction electrons with respect to the ionic positive background taking into account a free coefficient as a function of diameter of nanoparticle (NP) in the force term obtained by the idealistic Thomson model in order to adjust the classical approach. All important mechanisms of the energy dissipation such as electron-electron, electron-phonon and electron-NP surface scatterings and radiation are included in the model. In addition a correction term added to the damping factor of mentioned mechanisms in order to rectify the deficiencies of theoretical approaches. For determining the free parameters of model, the experimental data of extinction cross section of gold NPs with different sizes doped in the glass host medium are used and a good agreement between experimental data and results of our model is observed. It is shown that by decreasing the diameter of NP, the restoration force becomes larger and classical confinement effect becomes more dominant in the interaction. According to experimental data, the best fitted parameter for the coefficient of restoration force is a third order negative powers function of diameter. The fitted function for the correction damping factor is proportional to the inverse squared wavelength and third order power series of NP diameter. Based on the model parameters, the real and imaginary parts of permittivity for different sizes of gold NPs are presented and it is seen that the imaginary part is more sensitive to the diameter variations. Increase in the NP diameter causes increase in the real part of permittivity (which is negative) and decrease in the imaginary part. :1912.11245v1 [cond-mat.mtrl-sci] arXiv

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“…( 2) is related to the restoration force caused by the separation of electrons from the positive background ions and parameter ξ is for adjustment of experimental data with the theory. In most of theoretical studies related to the interaction of laser beam with MNPs [33][34][35][36][37][38][39][40], in an ideal case of rigid body approximation in which all conduction electrons are replaced equally, its value is 1/3, however in the real situation, its value depending on the diameter of NP is less than 1/3 and it vanishes for the large particles which shows the transition to bulk medium situation [32]. E 1 is the electric field at the place of the first NP which is the sum of the incident wave electric field E L and interaction term E 2→1 where E 2→1 is the electric field at the place of first NP r 01 caused by the electric dipole moment of the second NP (p 2 = −Zer 2 , where Z = n 0 V is the total conduction electrons of each NP and V is the volume of NP) that can be represented as…”

Section: Introductionmentioning

confidence: 99%

Analytical approach to the surface plasmon resonance characteristic of metal nanoparticle dimer in dipole-dipole approximation

Kheirandish¹,

Javan²,

Mohammadzadeh³

2020

Preprint

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This theoretical study, deals with the effect of bi-particle interaction on the surface plasmon resonance (SPR) in a dimer which includes two identical metal nanoparticles (NPs). Considering the dipole-dipole interaction in a Drude-like model, an appropriate equation is derived for the permittivity of each NP. The restoration force related to the classical confinement originating from the finite size of NPs is considered and an appropriate adjustment coefficient is considered for this term through analyzing experimental data. Two different polarizations are considered for the laser beam electric field and it is shown that the orientation of electric field has essential role in the linear optical properties of dimer. Numerical investigation is accomplished for a dimer of gold NPs with two different diameters of 4nm and 20nm. For the parallel polarization, dipole-dipole interaction leads to the red-shift of SPR wavelength and increase in its peak value while for the perpendicular polarization, the absolutely opposite results are derived. For all cases, it is shown that SPR wavelength functionality with respect to the geometric factor a/d (NP radius to the separation) can be presented by a cubic equation that fits better than an exponential one suggested by the earlier studies which demonstrates the dipole-dipole characteristic of the interaction. Qualitatively, our results are in good agreement with the other experimental studies.

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Magnetic field effect on the self-focusing of an intense laser pulse interacting with a bulk medium of graphite nanoparticles

Cited by 16 publications

References 39 publications

Hat-Top Beams for Generating Tunable THz Radiations Using a Medium of Conducting Nanocylinders

Hat-Top Beams for Generating Tunable THz Radiations Using a Medium of Conducting Nanocylinders

Modified Drude model for small gold nanoparticles surface plasmon resonance based on the role of classical confinement

Analytical approach to the surface plasmon resonance characteristic of metal nanoparticle dimer in dipole-dipole approximation

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