K. Porsezian

Pondicherry University, Pondichéry, Pondicherry, India

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Publications (236)316.25 Total impact

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    ABSTRACT: We study the amplitude perturbations of the cubic–quintic Gross–Piteavskii equation for weakly trapped Bose–Einstein condensates through a semiquantum procedure. After a quantization of the original problem, with the introduction of quantum degrees of freedom as the fluctuations around classical parameters, a new dynamical modulational instability condition is derived. Corrective terms bear quantum effects that play a crucial role over the reshape of instability domain and sometimes train all unstable modes into full stability. By making use of several indicators through direct numerical simulations of the subsequent set of equations of motion, we found that there are rooms of regular trajectories and those of totally chaotic ones that are strictly related to instability. These numerical results are in agreement with the analytical predictions regarding the stabilization of Bose–Einstein condensates.
    Chaos Solitons & Fractals 07/2015; 76. DOI:10.1016/j.chaos.2015.03.015 · 1.50 Impact Factor
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    Journal of the Optical Society of America B 06/2015; 32(6):1106. DOI:10.1364/JOSAB.32.001106 · 1.81 Impact Factor
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    ABSTRACT: We consider a next-higher-order extension of the Chen–Lee–Liu equation, i.e., a higher-order Chen–Lee–Liu (HOCLL) equation with third-order dispersion and quintic nonlinearity terms. We construct the n-fold Darboux transformation (DT) of the HOCLL equation in terms of the n × n determinants. Comparing this with the nonlinear Schrödinger equation, the determinant representation T n of this equation is involved with the complicated integrals, although we eliminate these integrals in the final form of the DT, so that the DT of the HOCLL equation is unusual. We provide explicit expressions of multi-rogue wave (RW) solutions for the HOCLL equation. It is concluded that the rogue wave solutions are likely to be crucial when considering higher-order nonlinear effects.
    Physica Scripta 05/2015; 90(5). DOI:10.1088/0031-8949/90/5/055207 · 1.30 Impact Factor
  • K Nithyanandan, K Porsezian
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    ABSTRACT: We investigate the modulational instability (MI) induced Supercontinuum generation (SCG) in exponential saturable nonlinearity. The pump power (P) is observed to behave in a unique way such that unlike the conventional Kerr case, the effective nonlinearity of saturable nonlinear system does not monotonously increases with an increase in power. The supercontinuum is observed at the shortest distance of propagation at power equal to the saturation power (Ps), whereas for all combinations of powers (P Ps or P > Ps) spectral broadening occurs at longer distance.
    Journal of Physics Conference Series 04/2015; 605(1). DOI:10.1088/1742-6596/605/1/012031
  • K Nithyanandan, K Porsezian
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    ABSTRACT: We investigate the modulational instability (MI) of the optical beam propagating in the relaxing saturable nonlinear system. We identify and discuss the salient features of various functional forms of saturable nonlinear responses such as exponential, conventional and coupled type on the MI spectrum. Using Debye relaxation model, the relaxation of nonlinear response is effectively included along with the saturable nonlinear response (SNL). Using linear stability analysis, an explicit dispersion relation is determined for considering different functional forms of SNL. Firstly, we analyze the impact of SNL on the MI spectrum and found that the MI gain and bandwidth is maximum for exponential nonlinearity in comparison to other types of SNL's. Latter the relaxation of the nonlinearity is included, the inclusion of the finite value of the response time extends the range of the unstable frequencies literally down to infinite frequencies. In the regime of slow response, the MI inevitably suppressed regardless of the sign of the dispersion coefficient. To give insight into the MI phenomena, the maximum MI gain and the optimum modulation frequency is drawn as a function of the delay. Thus the MI dynamics in the system of relaxing saturable nonlinear media is emphasized and the significance of various functional forms of SNL are highlighted.
    Journal of Physics Conference Series 04/2015; 605(1). DOI:10.1088/1742-6596/605/1/012032
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    ABSTRACT: We harness the freedom in the celebrated gauge transformation approach to generate dark solitons of coupled nonlinear Schr\"odinger (NLS) type equations. The new approach which is purely algebraic could prove to be very useful, particularly in the construction of vector dark solitons in the fields of nonlinear optics, plasma physics and Bose-Einstein condensates. We have employed this algebraic method to coupled Gross- Pitaevskii (GP) and NLS equations and obtained dark solitons.
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    S. Sabari, K. Porsezian, R. Murali
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    ABSTRACT: We explain how the modulational and oscillatory instabilities can be generated in Bose–Einstein condensates (BECs) with two- and three-body interactions trapped in a periodic optical lattice with driving harmonic potential. We solve a cubic–quintic Gross–Pitaevskii (GP) equation with external trapping potentials by using both analytical and numerical methods. Using the time-dependent variational approach, we derive and analyze the variational equations for the time evolution of the amplitude and phase of modulational perturbation, and effective potential of the system. Through the effective potential, we obtain the modulational instability condition of the BECs with two- and three-body interactions and shown the effects of the optical potential on the dynamics of the system. We perform direct numerical simulations to support our analytical results, and good agreement is observed.
    Physics Letters A 02/2015; DOI:10.1016/j.physleta.2013.12.047 · 1.63 Impact Factor
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    ABSTRACT: A variety of AS2S3 chalcogenide photonic crystal fiber coupler of special properties are proposed to study the role of birefringence in all optical coupling characteristics based on the projection operator method (POM). The equations of motion describing the dynamics of the individual pulse parameters through x- and y-polarized modes are arrived at by employing POM from the coupled nonlinear Schrödinger equations. From the pulse parameter dynamics, it is observed that the amplitudes of the polarization components are significantly influenced by the pulse being introduced with different polarizing angle even at low input power level. Such a selective polarizing angles of the input pulse will provide efficient control over the desired splitting ratio as well as the ability to decide the desired polarization component.
    Journal of optics 01/2015; 17(2):025504 (1-11). DOI:10.1088/2040-8978/17/2/025504 · 2.01 Impact Factor
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    ABSTRACT: We investigate the modulation instability (MI) in a three-core oppositely-directed coupler with a particular emphasis on a negative index material (NIM) channel. In order to give a comprehensive picture, we consider the normal and the anomalous dispersion regimes. Special attention is paid to investigation of the influence of system parameters such as the power and the coupling coefficient on the MI. We also analyze the impact of different nonlinear configurations of coupler channels on MI
    Physics Letters A 01/2015; 379:223. · 1.63 Impact Factor
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    ABSTRACT: We present a novel asymmetric triple core photonic crystal fiber for the construction of NOR and OR logic gates by employing all optical control. Through extinction ratio calculated at apt control signal phase, the Boolean algebra for NOR and OR logic gates are demonstrated numerically.
    International Conference on Fibre Optics and Photonics, IIT, Kharagpur India; 12/2014
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    ABSTRACT: A highly nonlinear CS2 filled liquid core PCF (LCPCF) is proposed to study the supercontinuum generation. It is observed that the novel design of LCPCF make suitable for highly scattering tissue optical coherence tomography applications.
    International Conference on Fibre Optics and Photonics, IIT, Kharagpur India; 12/2014
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    ABSTRACT: We find self-trapped propagation of elliptical super-Gaussian beam in cubic–quintic nonlinear media. The soliton beam preserves its shape and size during propagation in Kerr media. Both defocusing and focusing quintic nonlinearities are considered. In a cubic (focusing)-quintic (defocusing) media breather like beam propagation with intriguing beam width oscillation is observed. The influence of beam ellipticity, super-Gaussian nature and quintic nonlinearity on self-trapping has been studied. A formula for critical power for self-focusing has been derived and it readily agrees with the results obtained by variational method. In Kerr and focusing quintic media beam collapse occurs quicker for higher order super-Gaussian beam. The critical power of self-focusing in defocusing (focusing) quintic medium prominently increases (decreases) with increasing strength of quintic nonlinearity. This variation rate is greater for higher order super Gaussian beam. A beam with greater ellipticity requires larger power for self-trapping.
    Optics Communications 12/2014; 332:311–320. DOI:10.1016/j.optcom.2014.06.061 · 1.54 Impact Factor
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    ABSTRACT: We investigate the modulation instability in oppositely directed coupler in the presence of higher-order effects. Using linear stability analysis, we obtain an expression for instability gain. Special attention is paid to find out the influence of self-steepening effect and intrapulse Raman scattering on modulation instability. The study shows that in normal dispersion, regime instability gain exists even if perturbation frequency (Ω) is zero. But the instability gain at Ω=0 is zero, when the dispersion is anomalous. Moreover, self-steepening effect and intrapulse Raman scattering form new instability regions and, hence, provide a new way to generate solitons or ultrashort pulses. Further, efficient control of modulation instability by adjusting self-steepening effect and intrapulse Raman scattering also successfully demonstrated.
    Physical Review E 10/2014; 90(4-1):042910. DOI:10.1103/PhysRevE.90.042910 · 2.33 Impact Factor
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    T. Mithun, K. Porsezian, Bishwajyoti Dey
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    ABSTRACT: We study the vortex dynamics and vortex pinning effect in Bose-Einstein condensate in a rotating double-well trap potential and co-rotating optical lattice. We show that, in agreement with the experiment, the vortex number do not diverge when the rotational frequency $\Omega \rightarrow 1$ if the trap potential is of anisotropic double-well type. The critical rotational frequency as obtained from numerical simulations agrees very well with the value $\sqrt l/l$ for $l=4$ which supports the conjecture that surface modes with angular momentum $l=4$ are excited when the rotating condensate is trapped in double-well potential. The vortex lattice structure in a rotating triple-well trap potential and its pinning shows very interesting features. We show the existence and pinning of a new type of hidden vortices whose phase profile is similar to that of the visible vortices.
    Physical Review A 08/2014; 89(5). DOI:10.1103/PhysRevA.89.053625 · 2.99 Impact Factor
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    ABSTRACT: We have proposed a novel APCFCs for multi-frequency generation and its optical performance for generating new frequency components are studied numerically by using SSFM. For our study, we have considered two cases namely one with same GVD and different nonlinearity and the other with different GVD as well as nonlinearity. From the results obtained, we are able to demonstrate considerable new frequency generation within a shorter distance. In particular, APCFC with different nonlinearity as well as GVD exhibits the better new frequency generation. Hence, by preparing such APCFC of greater length one can realize a significantly broader frequency spectrum.
    22nd National Laser Symposium, Manipal University, Manipal, Karnataka, India.; 08/2014
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    ABSTRACT: In this paper, we consider the complex modified Korteweg-de Vries (mKdV) equation as a model of few-cycle optical pulses. Using the Lax pair, we construct a generalized Darboux transformation and systematically generate the first-, second- and third-order rogue wave solutions and analyze the nature of evolution of higher-order rogue waves in detail. Based on detailed numerical and analytical investigations, we classify the higher-order rogue waves with respect to their intrinsic structure, namely, fundamental pattern, triangular pattern, and ring pattern. We also present several new patterns of the rogue wave according to the standard and non-standard decomposition. The results of this paper explain the generalization of higher-order rogue waves in terms of rational solutions. We apply the contour line method to obtain the analytical formulas of the length and width of the first-order RW of the complex mKdV and the NLS equations. In nonlinear optics, the higher-order rogue wave solutions found here will be very useful to generate high-power few-cycle optical pulses which will be applicable in the area of ultra-short pulse technology.
    Physical Review E 05/2014; 89(6-1). DOI:10.1103/PhysRevE.89.062917 · 2.33 Impact Factor
  • R Radha, P S Vinayagam, K Porsezian
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    ABSTRACT: We study the dynamics of spatially coupled Bose-Einstein condensates and generate bright and dark solitons employing gauge transformation approach. We observe that when bright/dark solitons evolve in time, the centre of localization of the wave packet gets shifted to the left. We also notice that the spatial coupling stretches the wave packet which can be used as a mechanism to stabilize the condensates. The impact of spatial coupling is suitably exploited to generate an interference pattern in the collision of bright-bright, dark-dark and dark-bright solitons.
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    ABSTRACT: We investigate the dynamical instability of Bose-Einstein condensates (BECs) with higher-order interactions immersed in an optical lattice with weak driving harmonic potential. For this, we compute both analytically and numerically a modified Gross-Pitaevskii equation with higher-order nonlinearity and external potentials generated by magnetic and optical fields. Using the time-dependent variational approach, we derive the ordinary differential equations for the time evolution of the amplitude and phase of modulational perturbation. Through an effective potential, we obtain the modulational instability condition of BECs and discuss the effect of the higher-order interaction in the dynamics of the condensates in presence of optical potential. We perform direct numerical simulations to support our analytical results, and good agreement is found.
    Physical Review E 04/2014; 89(5-1). DOI:10.1103/PhysRevE.89.052917 · 2.33 Impact Factor
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    T. Mithun, K. Porsezian, Bishwajyoti Dey
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    ABSTRACT: We derive analytically the Feynman rule for the vortex number of a Bose-Einstein condensate in a rotating double-well potential. From the numerical simulations of the two-dimensional Gross-Pitaevskii equation we show that the double-well potential gives rise to hidden vortices in addition to the usual visible vortices. The Feynman rule matches with the total number of these two types of vortices. We show that, unlike the isotropic case, the vortex number do not diverge at Ο = 1 for the anisotropic case. We further show that the Feynman rule is also satisfied when the condensate is loaded in a co-rotating optical lattice.
    03/2014; 1591(1). DOI:10.1063/1.4872508
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    L. H. Wang, K. Porsezian, J. S. He

Publication Stats

2k Citations
316.25 Total Impact Points

Institutions

  • 2003–2015
    • Pondicherry University
      • Department of Physics
      Pondichéry, Pondicherry, India
  • 1993–2002
    • Anna University, Chennai
      • Department of Physics
      Chennai, Tamil Nadu, India
  • 1987–1998
    • Bharathidasan University
      • • Department of Physics
      • • Centre for Non-Linear Dynamics
      Tiruchchirāppalli, State of Tamil Nadu, India