Speaker
Description
Fano-type resonance phenomena originate from quantum interference between excitations involving discrete and continuum states, giving rise to characteristic asymmetric spectral response profiles, which are highly sensitive to changes in resonance energy, linewidth, discrete-continuum coupling strength, and the surrounding environment. Such line shapes are ubiquitous in atomic, molecular and condensed-matter systems, particularly in plasmonic nanostructures and nanophotonic materials. Despite the considerable interest in these phenomena, disentangling subtle spectral variations and correlated changes of the Fano parameters remains rather challenging using conventional one-dimensional spectroscopic approaches.
In the present work, we employ several variants of two-dimensional correlation spectroscopy (2DCOS) to investigate the evolution of Fano resonance line shapes under different external perturbations. Dynamic spectra generated through systematic variations of the asymmetry parameter, resonance energy, linewidth and coupling strength are used to construct the generalized synchronous and asynchronous correlation maps. Characteristic cross-peak patterns are identified, enabling discrimination between frequency shifts, linewidth variations and changes in spectral asymmetry, and allowing the construction of a corresponding library of 2DCOS fingerprints. We further establish correlations between the physical mechanisms governing the Fano line-shape evolution and the topology of the corresponding two-dimensional correlation patterns. In addition to the generalized 2DCOS approach, we present a detailed analysis based on autocorrelation moving window two-dimensional correlation spectroscopy (MW-2DCOS) and perturbation-correlation MW-2DCOS (PC-MW-2DCOS) applied to the same datasets.
The simulation results are compared with experimental data for plasmonic semiconductor quantum dots, in which pronounced plasmon – exciton coupling gives rise to distinct Fano-type features in both optical absorption and photoluminescence spectra.
These results establish 2DCOS as a sensitive tool for decoding the dynamics of Fano resonances and for elucidating the mechanisms underlying their spectral evolution, as well as probing e.g. plasmon-exciton interactions in strongly coupled nanoscale systems.
Keywords: Fano resonance, Fano line shapes, plasmonic semiconductor quantum dots, two-dimensional correlation spectroscopy (2DCOS), plasmon-exciton coupling, optical absorption, photoluminescence.