Condensed Matter Physics, Spectroscopy, Materials Science, Modeling and Simulation
3
Scopus Publications
17
Scholar Citations
2
Scholar h-index
1
Scholar i10-index
Scopus Publications
Optical transmission and spectroscopic ellipsometry data of fused Quartz: Estimating dielectric function with Krönig-Kramers analysis Sanat Kumar Gogoi, Harshavardhan Reddy Kalluru Data in Brief, 2026 The manuscript discusses the procedure of estimating refractive index from optical transmission data of a solid material. Fused Quartz is used as the standard sample in this manuscript. First the refractive index data is measured directly using the spectroscopic ellipsometry technique. Subsequently, the transmission data is collected with a transmission spectrometer. The transmission data is then converted into extinction coefficient and subsequently transformed in to refractive index, by direct Krönig-Kramers (KK) analysis code. Further using singly and doubly subtractive KK analysis, the refractive index is estimated. The derived set of refractive indices from KK analysis, are then compared to the measured spectroscopic ellipsometry data. The refractive index and extinction coefficient are then used to estimate the relative dielectric permittivity function of the material.
Selectively Strong Coupling of Mo S2 Excitons to a Metamaterial at Room Temperature Harshavardhan R. Kalluru, Jaydeep K. Basu Physical Review Applied, 2022 Light emitters in the vicinity of a hyperbolic metamaterial (HMM) show a range of quantum optical phenomena from spontaneous decay-rate enhancement to strong coupling. In this study, we integrate a monolayer molybdenum disulfide (${\mathrm{Mo}\mathrm{S}}_{2}$) emitter in the near-field region of the HMM. The ${\mathrm{Mo}\mathrm{S}}_{2}$ monolayer has $A$ and $B$ excitons, which emit in the red region of the visible spectrum. We find that the $B$ excitons couple to the HMM differently compared to $A$ excitons. The fabricated HMM transforms to a hyperbolic dispersive medium at 2.14 eV, from an elliptical dispersive medium. The selective coupling of $B$ excitons to the HMM modes is attributed to the inbuilt field gradient of the transition. The $B$ exciton energy lies close to the transition point of the HMM, relative to the $A$ exciton. So, the HMM modes couple more to the $B$ excitons and the metamaterial functions as a selective coupler. The coupling strength calculations show that coupling is 2.5 times stronger for $B$ excitons relative to $A$ excitons. High near field of HMM, large magnitude, and the in-plane transition dipole moment of ${\mathrm{Mo}\mathrm{S}}_{2}$ excitons, result in strong coupling of $B$ excitons and formation of hybrid light-matter states. The measured differential reflection and photoluminescence spectra indicate the presence of hybrid light-matter states, i.e., exciton polaritons. Rabi splitting of $143.5\phantom{\rule{0.2em}{0ex}}\mathrm{meV}\ifmmode\pm\else\textpm\fi{}14.4$ meV at room temperature is observed. The low-temperature photoluminescence measurement shows mode anticrossing, which is a characteristic feature of hybrid states. Our results show that the HMM works as an energy-selective coupler for multiexcitonic systems as ${\mathrm{Mo}\mathrm{S}}_{2}$.
Spontaneous emission dynamics of Eu3+ions coupled to hyperbolic metamaterials Gabriel I. López-Morales, Mingxing Li, Ravindra K. Yadav, Harshavardhan R. Kalluru, Jaydeep K. Basu, Carlos A. Meriles, Vinod M. Menon Applied Physics Letters, 2021 Sub-wavelength nanostructured systems with tunable electromagnetic properties, such as hyperbolic metamaterials (HMMs), provide a useful platform to tailor spontaneous emission processes. Here, we investigate a system comprising Eu3+(NO3)3·6H2O nanocrystals on an HMM structure featuring a hexagonal array of Ag nanowires in a porous Al2O3 matrix. The HMM-coupled Eu3+ ions exhibit up to a 2.4 fold increase in their decay rate, accompanied by an enhancement of the emission rate of the 5D0 → 7F2 transition. Using finite-difference time-domain modeling, we corroborate these observations with the increase in the photonic density of states seen by the Eu3+ ions in the proximity of the HMM. Our results indicate that HMMs can serve as a valuable tool to control the emission from weak transitions and, hence, hint at a route toward more practical applications of rare-earth ions in nanoscale optoelectronics and quantum devices.
RECENT SCHOLAR PUBLICATIONS
Optical transmission and spectroscopic ellipsometry data of fused Quartz: Estimating dielectric function with Krönig-Kramers analysis SK Gogoi, HR Kalluru Data in Brief 66, 112781 , 2026 2026
Spectroscopic study of emitter assemblies coupled to Plasmonic nano-cavities and metamaterials HR Kalluru Indian Institute of Science Bengaluru , 2023 2023
Inhibited spontaneous emission of quantum dots weakly coupled to off resonant silver nanoplatelets and silver nanowires HR Kalluru, B Tongbram, A Biswas, JK Basu arXiv preprint arXiv:2301.08702 , 2023 2023 Citations: 1
Evaluating the transition dipole moment of quantum dots with absorption and angle resolved photo-luminescence spectroscopy HR Kalluru, B Tongbram, JK Basu arXiv preprint arXiv:2212.13510 , 2022 2022 Citations: 1
Selectively Strong Coupling of MoS2 Excitons to a Metamaterial at Room Temperature JKB Harshavardhan R. Kalluru Phys. Rev. Applied 18 (1), 014004 , 2022 2022 Citations: 5
Exciton-Polaritons in monolayer molybdenum disulphide coupled to hyperbolic metamaterial HR Kalluru, JK Basu APS March Meeting Abstracts 2022, M31. 006 , 2022 2022
Spontaneous emission dynamics of Eu3+ ions coupled to hyperbolic metamaterials GI López-Morales, M Li, RK Yadav, HR Kalluru, JK Basu, CA Meriles, ... Applied Physics Letters 118 (1) , 2021 2021 Citations: 10
MOST CITED SCHOLAR PUBLICATIONS
Spontaneous emission dynamics of Eu3+ ions coupled to hyperbolic metamaterials GI López-Morales, M Li, RK Yadav, HR Kalluru, JK Basu, CA Meriles, ... Applied Physics Letters 118 (1) , 2021 2021 Citations: 10
Selectively Strong Coupling of MoS2 Excitons to a Metamaterial at Room Temperature JKB Harshavardhan R. Kalluru Phys. Rev. Applied 18 (1), 014004 , 2022 2022 Citations: 5
Inhibited spontaneous emission of quantum dots weakly coupled to off resonant silver nanoplatelets and silver nanowires HR Kalluru, B Tongbram, A Biswas, JK Basu arXiv preprint arXiv:2301.08702 , 2023 2023 Citations: 1
Evaluating the transition dipole moment of quantum dots with absorption and angle resolved photo-luminescence spectroscopy HR Kalluru, B Tongbram, JK Basu arXiv preprint arXiv:2212.13510 , 2022 2022 Citations: 1
Optical transmission and spectroscopic ellipsometry data of fused Quartz: Estimating dielectric function with Krönig-Kramers analysis SK Gogoi, HR Kalluru Data in Brief 66, 112781 , 2026 2026
Spectroscopic study of emitter assemblies coupled to Plasmonic nano-cavities and metamaterials HR Kalluru Indian Institute of Science Bengaluru , 2023 2023
Exciton-Polaritons in monolayer molybdenum disulphide coupled to hyperbolic metamaterial HR Kalluru, JK Basu APS March Meeting Abstracts 2022, M31. 006 , 2022 2022
