arXiv subjects

Amit Haldar

Publications and source records attributed to Amit Haldar.

2 recordsLinked to original sources

arXiv2025

Unveiling nonlinearities of electromagnetically induced transparency in a THz metamaterial

Electromagnetically induced transparency (EIT) in terahertz (THz) metamaterials relies on the coherent coupling between a radiative (bright) mode and a subradiant (dark) mode. Understanding the dynamic interplay between the bright and dark modes holds the key to manipulate the mutual interference and hence the transparency. Here, we use nonlinear 2D-THz spectroscopy to scrutinize the dynamics through nonlinearities of the EIT-like phenomenon in a metamaterial platform that comprises of two coupled resonators. From the temporal profiles of the nonlinear pump-probe and photon-echo signals, we found that the bright mode relaxation time is almost twice the time for the coherent exchange of energy between the two coupled resonators. The multi-peak nature of photon-echo signal and the corresponding temporal signatures further provides a direct visualization of the interference between the dressed states that drives the transparency window in our THz metamaterial. A time-resolved density matrix model accurately describes the observed features, including the cross-peak behavior and the temporal dynamics, establishing the coherent mode coupling as the origin of the transparency window.

physics.optics↗

arXiv2025

Phonon-polariton mediated dual electromagnetically induced transparency-like response in a THz metamaterial

Light and matter can intertwine to create entirely new quantum states in the so-called strong-coupling regime, allowing unprecedented control over electromagnetic waves. In this work, strong-coupling mediated polaritonic states are exploited to demonstrate tunable dual electromagnetically induced transparency (EIT) like response in the terahertz (THz) frequency range using a micron-sized metamaterial system coupled with the phonon mode of a lead halide perovskite film. This architecture allows us to reversibly switch between the single and the dual EIT-like behavior without modifying the metamaterial structures. The dual EIT-like nature is further confirmed through the in-plane electric field distributions and the slow-light effects. The specific structural symmetry further allowed us to effectively switch between the dual EIT-like response and the conventional strong-coupling responses. Such tunability bears potential implications for developing metamaterial-phonon-based tunable THz devices such as switches, filters, and slow-light devices.

physics.optics↗