A1 Journal article (refereed)
Effect of molecular concentration on excitonic nanostructure based refractive index sensing and near-field enhanced spectroscopy (2023)

Dutta, A., & Toppari, J. J. (2023). Effect of molecular concentration on excitonic nanostructure based refractive index sensing and near-field enhanced spectroscopy. Optical Materials Express, 13(8), 2426-2445. https://doi.org/10.1364/OME.497366

JYU authors or editors

Publication details

All authors or editorsDutta, Arpan; Toppari, J. Jussi

Journal or seriesOptical Materials Express


Publication year2023


Issue number8

Pages range2426-2445

PublisherOptica Publishing Group

Publication countryUnited States

Publication languageEnglish


Publication open accessOpenly available

Publication channel open accessOpen Access channel

Publication is parallel published (JYX)https://jyx.jyu.fi/handle/123456789/89017

Web address of parallel published publication (pre-print)https://chemrxiv.org/engage/chemrxiv/article-details/646cc283b3dd6a65309a19e9


Organic thin film based excitonic nanostructures are of great interest in modern resonant nanophotonics as a promising alternative for plasmonic systems. Such nanostructures sustain propagating and localized surface exciton modes that can be exploited in refractive index sensing and near-field enhanced spectroscopy. To realize these surface excitonic modes and to enhance their optical performance, the concentration of the excitonic molecules present in the organic thin film has to be quite high so that a large oscillator strength can be achieved. Unfortunately, this often results in a broadening of the material response, which might prevent achieving the very goal. Therefore, systematic and in-depth studies are needed on the molecular concentration dependence of the surface excitonic modes to acquire optimal performance from them. Here, we study the effect of molecular concentration in terms of oscillator strength and Lorentzian broadening on various surface excitonic modes when employed in sensing and spectroscopy. The optical performance of the modes is evaluated in terms of sensing, like sensitivity and figure of merit, as well as near-field enhancement, like enhancement factor and field confinement. Our numerical investigation reveals that, in general, an increase in oscillator strength enhances the performance of the surface excitonic modes while a broadening degrades that as a counteracting effect. Most of all, this demonstrates that the optical performance of an excitonic system is tunable via molecular concentration unlike the plasmonic systems. Moreover, different surface excitonic modes show different degrees of tunability and equivalency in performance when compared to plasmons in metals (silver and gold). Our findings provide crucial information for developing and optimizing novel excitonic nanodevices for contemporary organic nanophotonics.


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Ministry reportingYes

Reporting Year2023

JUFO rating2

Last updated on 2024-15-05 at 13:22