Optical microcavity exciton-polaritons
Attractive Coulomb interaction between a pair of electron and hole gives rise to excitonic states in a solid. A gas of Wannier-Mott excitons can be confined in two dimensions by growing artificial heterostructures of semiconductors. One of the breakthrough in condensed matter and materials sciences in the last decade is the discovery of mechanical exfoliation technique to obtain graphene and graphene like two dimensional semiconductors. We can now realize a two dimensional gas of strongly bound excitons in these atomically thin two dimensional semiconductors. One of the research direction of our group is to explore the rich physics of light-matter interaction in the regime of cavity quantum electrodynamics using these two dimensional materials inside an optical cavity.
“Anomalous dispersion of microcavity trion-polaritons”- Nature Physics, volume 14, pages 130–133 (2018)
Nanoscale Photocurrent Spectroscopy
We use Circular Photogalvanc Effect (CPGE), where the angular momentum of light is utilized to excite photo generated carriers with certain spin or orbital angular momentum at a particular energy-momentum point in the bandstructure. One of our research interest is to use this technique to explore new ideas from topological band theories.
“Voltage-tunable circular photogalvanic effect in silicon nanowires”- Science, volume 349, pages 726-729 (2015)