Research

Topological Insulator and Chalcogenide based Meta-Optics

In nanophotonics, small mode volume and high quality factor (Q-factor) resonances fundamentally scales with the refractive index values. Chalcogenides are excellent candidates for implementing nanophotonic and metasurface devices as they can possess ultrahigh permittivities and support large modulation of optical constants through various mechanisms such as, phase-change, photondarkening, and anomalous thermo-optic effects. Topological insulators (TIs) are a new class of materials possessing narrow bulk bandgap along with gapless Dirac surface states characterized by strong spin orbit coupling making them robust against defects. In the context of optical properties, chalcogenide TIs have recently been of interest due to their narrow bulk bandgap and extremely high permittivity values, leading to index values as high as n≈11 (in the IR). These ultra-high refractive index values can then be utilized for demonstrating ultracompact, deep-subwavelength meta-atoms and metasurface.

S. Nandi et al., Advanced Optical Materials, 2024S. Nandi et al., Nano Letters, 2023S. Nandi et al., CLEO, 2023D. Singh, S. Nandi, et al., Laser & Photonics Reviews, 2023S. Z. Cohen, D. Singh, S. Nandi, T. Lewi, Nanophotonics, 2023M. Poplinger, D. Kaltsas, C. Stern, P. Nanikashvili, A. Levi, R. K. Yadav, S. Nandi, et al., Journal of Materials Chemistry C, 2024

scattering-type Scanning Near-field Optical Microscopy (s-SNOM)

s-SNOM based nanoscopy is a powerful technique for characterizing nanophotonic systems, material identification, and probing exotic nanoscale and quantum phenomenon with 10−20 nm spatial resolution (even for IR wavelengths, thus overcoming wavelength limited diffraction limit). This technique allows us to gather local information that is either lost or averaged out in the far-field response as well as to couple into excitations (such as quasiparticles, e.g., phonon-polaritons) which are difficult to access from the far-field.

S. Nandi et al., Advanced Optical Materials, 2024S. Nandi et al., NANOMETA, 2024S. Nandi et al., Nano Letters, 2023S. Nandi et al., CLEO, 2023

Optoelectronics with low-dimensional and exotic materials

The current technological revolution towards miniaturized and portable electronic devices demand functionalities- such as, high-efficiency, mechanical flexibility and low power consumptions. Low-dimensional materials are unique platforms for realizing these functionalities owing to their enhanced light-matter interaction and unique detection schemes (such as pyro-phototronic effect, plasmonic effects and so on). On the other hand, exotic materials, such as Mott-insulators, can result in fast-switching and high responsivity optoelectronic devices upon operating them at their transition temperatures.

V. Panwar, M. Dey, P. Sharma, S. Karthick, S. Nandi, et al., Small, 2024S. Nandi et al., Journal of Applied Physics, 2023S. Nandi, A. Misra, ACS Materials Letters, 2022S. Nandi et al., Advanced Materials Interfaces, 2020S. Nandi, A. Misra, ACS applied materials & interfaces, 2019B.D. Boruah, S.N. Majji, S. Nandi, A. Misra, Nanoscale, 2018

Page updated

Google Sites

Report abuse