Physics Research Seminar by Dr. Dheeraj Pratap on “Nanostructured electromagnetic metamaterials and nanoscale heat transfer” | Shiv Nadar University
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Physics Research Seminar by Dr. Dheeraj Pratap on “Nanostructured electromagnetic metamaterials and nanoscale heat transfer”

Metamaterials are artificially designed composite materials that are structured on sub-wavelength length scales. They are often inherently optically anisotropic, having direction dependent properties, due to their structure.  Acid anodization of an aluminium microwire has been used to fabricate a nanoporous alumina microtube with non-branching nanopores aligned along the radial direction. This is essentially a metamaterial with anisotropy in the cylindrical geometry. These cylindrical nanoporous alumina structures are not only anisotropic, but they are radially inhomogeneous as well due to the radius dependent size of the nanopores. Obtained metamaterials have been homogenized to obtain the electromagnetic effective medium parameters (dielectric permittivity tensor) using techniques of transformation optics and Maxwell-Garnett homogenisation theory. Nanowires of silver metal have been deposited electrochemically within the nanopores of the cylindrical nanoporous alumina to yield a metamaterial with hyperbolic dispersion. These metamaterial fibers exhibit novel optical modes that are described by Bessel functions of fractional and imaginary orders solely due to the anisotropy. Particularly for the high transverse momentum modes, these modes are confined increasing near the centre of the waveguide in sheer contrast to conventional fibers where they localise to the edge. The inhomogeneous nature of the metamaterial fibres also causes extremely strong confinement of the modes near the center. Application of nanoporous alumina as metamaterial heat exchanger also has been investigated

Event Date: 
Monday, April 15, 2019 -

Speaker   :   Dr. Dheeraj Pratap

                    Metamaterials & Plasmonics Laboratory, Department of Physics, IIT Kanpur

Monday 15, Apr 2019
12:00 PM - 01:00 PM