S Dutta Gupta
Articles written in Pramana – Journal of Physics
Volume 61 Issue 3 September 2003 pp 563-575
We study the effect of a nearby phase-conjugate mirror (PCM) on the gap soliton of a Kerr non-linear periodic structure. We show that phase conjugation of the gap soliton (in the sense of replication of the amplitude profile in the reverse direction) is possible under the condition of PCM reflectivity approaching unity. This is in contrast with the results for linear structures, where the wave profiles can be conjugated for arbitrary values of the PCM reflectivity. The sensitivity of the conjugation of the gap solitons to PCM reflectivity is ascribed to the fine balance of non-linearity with dispersion, necessary for their existence.
Volume 72 Issue 2 February 2009 pp 303-314 Rapid Communication
We study the dispersion relation and the modes of a symmetric gap plasmon guide, where a dielectric planar slab is coated with finite metallic layers on both top and bottom. The finite conductivity of the metal is taken into account. The modes of the structure exhibit significant differences from those of dielectric waveguides with air or metal as the bounding media. Avoided level crossing phenomenon between the plasmon and the guided modes is shown to exist, leading to leaky modes. The structure sandwiched between two high index media is shown to lead to slow light in transmission. The group delay is shown to be larger for higher order modes.
Volume 75 Issue 5 November 2010 pp 837-854 Invited Papers
We present a quantitative study of the effects of losses in layered media with a metamaterial layer as the constituent. The metamaterial is modelled by a causal isotropic effective medium (Lorentz-type) response. The parameters for the model are picked from a recent experiment. Two specific examples, namely, that of resonant tunnelling (RT) and imaging are chosen to demonstrate the devastating effects of losses in the present day metamaterials. It is then shown how large delays in RT, as well as near perfect imaging can be restored in gain-doped metamaterials. We also point out yet another use of metamaterials for achieving near perfect absorption, and its use for probing strong atom–field interaction.
Volume 76 Issue 4 April 2011 pp 603-612
We study the reﬂection of a Hermite–Gaussian beam at an interface between two dielectric media. We show that unlike Laguerre–Gaussian beams, Hermite–Gaussian beams undergo no signiﬁcant distortion upon reﬂection. We report Goos–Hänchen shift for all the spots of a higherorder Hermite–Gaussian beam near the critical angle. The shift is shown to be insigniﬁcant away from the critical angle. The calculations are carried out neglecting the longitudinal component along the direction of propagation for a spatially ﬁnite, s-polarized, full 3D vector beam. We brieﬂy discuss the difﬁculties associated with the paraxial approximation pertaining to a vector Gaussian beam.
Volume 95, 2021
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