Thejaswi Tumkur

Dr. Thejaswi Tumkur

Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
orcid

Research Focus & Metrics

Academic Career Length

18Years (2009-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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13 April 2009 in Applied Physics Letters
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Journal Article
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MNM. A. Noginov
M. A. Noginov
YBYu. A. Barnakov
Yu. A. Barnakov
GZG. Zhu
G. Zhu
TTThejaswi Tumkur
Thejaswi Tumkur
HLH. Li
H. Li
ENE. E. Narimanov
E. E. Narimanov
We have demonstrated the thickest bulk photonic metamaterial reported in the literature based on an Ag-filled alumina membrane. The material is highly anisotropic with hyperbolic dispersion at λ>0.84 μm . The refraction of light in the direction expected of isotropic media with n<1 has been experimentally demonstrated at λ=632.8 nm . This makes the material potentially suitable for a variety of applications ranging from subdiffraction imaging to optical cloaking.

10 October 2011 in Applied Physics Letters
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Journal Article
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TTThejaswi Tumkur
Thejaswi Tumkur
GZG. Zhu
G. Zhu
PBP. Black
P. Black
YBYu. A. Barnakov
Yu. A. Barnakov
CBC. E. Bonner
C. E. Bonner
MNM. A. Noginov
M. A. Noginov
We have developed a simple method to fabricate lamellar metal-dielectric hyperbolic metamaterials on flat, flexible, and curvilinear substrates, which allows for functionalization of dielectric layers by dye molecules. The control of spontaneous emission of dye molecules with hyperbolic metamaterials has been studied in two different sample configurations, and the effect has been found to be much stronger when emitters are placed inside the metamaterial rather than on its surface.

27 September 2010 in Applied Physics Letters
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LAL. V. Alekseyev
L. V. Alekseyev
ENE. E. Narimanov
E. E. Narimanov
TTThejaswi Tumkur
Thejaswi Tumkur
HLH. Li
H. Li
YBYu. A. Barnakov
Yu. A. Barnakov
MNM. A. Noginov
M. A. Noginov
We describe a unique class of metamaterials that exhibit strong uniaxial anisotropy with epsilon-zero response along the optical axis and which optical properties depend strongly on polarization. In an example of array of silver nanowires grown in anodic alumina membrane, the proposed singular uniaxial metamaterial is shown to function as a polarizer and narrowband angular transmittance filter.

17 September 2021 in Science Advances
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Journal Article
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TTThejaswi Tumkur
Thejaswi Tumkur
TVThomas Voisin
Thomas Voisin
Rongpei ShiRongpei Shi
Rongpei Shi
PDPhilip J. Depond
Philip J. Depond
TRTien T. Roehling
Tien T. Roehling
MMManyalibo J. Matthews
Manyalibo J. Matthews
Beam shape engineering in the form of propagation-invariant Bessel beams significantly improves metal additive manufacturing.

16 April 2012 in Applied Physics Letters
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Journal Article
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TTThejaswi Tumkur
Thejaswi Tumkur
LGLei Gu
Lei Gu
JKJ. K. Kitur
J. K. Kitur
ENE. E. Narimanov
E. E. Narimanov
MNM. A. Noginov
M. A. Noginov
We show that absorption of thin dye-doped polymeric films can be tuned and enhanced (nearly threefold) by metallic and lamellar metal-dielectric hyperbolic metamaterial substrates. The effect can be controlled by a combination of the substrate’s geometry and composition. As the enhancement of absorption is sustained over large range of incidence angles, the demonstrated phenomenon can lead to a variety of important applications, including solar cell technology.

14 November 2014 in Faraday Discussions
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Journal Article
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TTThejaswi Tumkur
Thejaswi Tumkur
JKJ. K. Kitur
J. K. Kitur
CBC. E. Bonner
C. E. Bonner
APA. N. Poddubny
A. N. Poddubny
ENE. E. Narimanov
E. E. Narimanov
MNM. A. Noginov
M. A. Noginov
Optical cavities, plasmonic structures, photonic band crystals and interfaces, as well as, generally speaking, any photonic media with homogeneous or spatially inhomogeneous dielectric permittivity (including metamaterials) have local densities of photonic states, which are different from that in vacuum. These modified density of states environments are known to control both the rate and the angular distribution of spontaneous emission. In the present study, we question whether the proximity to metallic and metamaterial surfaces can affect other physical phenomena of fundamental and practical importance. We show that the same substrates and the same nonlocal dielectric environments that boost spontaneous emission, also inhibit Förster energy transfer between donor and acceptor molecules doped into a thin polymeric film. This finding correlates with the fact that in dielectric media, the rate of spontaneous emission is proportional to the index of refractionn, while the rate of the donor–acceptor energy transfer (in solid solutions with a random distribution of acceptors) is proportional ton−1.5. This heuristic correspondence suggests that other classical and quantum phenomena, which in regular dielectric media depend onn, can also be controlled with custom-tailored metamaterials, plasmonic structures, and cavities.