• S K Golam Ali

      Articles written in Pramana – Journal of Physics

    • Effects of three-body atomic interaction and optical lattice on solitons in quasi-one-dimensional Bose–Einstein condensate

      S K Golam Ali B Talukdar Aparna Saha

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      We make use of a coordinate-free approach to implement Vakhitov–Kolokolov criterion for stability analysis in order to study the effects of three-body atomic recombination and lattice potential on the matter–wave bright solitons formed in Bose–Einstein condensates. We analytically demonstrate that (i) the critical number of atoms in a stable BEC soliton is just half the number of atoms in a marginally stable Townes-like soliton and (ii) an additive optical lattice potential further reduces this number by a factor of $\sqrt{1 − b_{g3}$ with $g_{3}$ the coupling constant of the lattice potential and $b = 0.7301$.

    • Evolution of optical pulses in the presence of third-order dispersion

      Debabrata Pal S K Golam Ali B Talukdar

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      We model the propagation of femtosecond pulses through optical fibres by a nonlinear Schrödinger (NLS) equation involving a perturbing term arising due to third-order dispersion in the medium. The perturbative effect of this higher-order dispersion causes the usual NLS soliton to emit a radiation field. As a result, the given initial pulse propagating through the fibre exhibits nonsolitonic behaviour. We make use of a variational method to demonstrate how an initial pulse by the interaction with the emitted radiation can evolve into a soliton. We also demonstrate that the effect of interaction between the initial pulse and radiation field can be accounted for by including, in the evolution equation, terms associated with self-steepening and stimulated Raman scattering that characterize the optical medium.

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