2020, Dovzhenko, D., Krivenkov, V., Kriukova, I., Samokhvalov, P., Nabiev, I., Крюкова, Ирина Сергеевна, Самохвалов, Павел Сергеевич, Набиев, Игорь Руфаилович

Photoluminescence (PL)-based sensing techniques have been significantly developed in practice due to their key advantages in terms of sensitivity and versatility of the approach. Recently, various nanostructured and hybrid materials have been used to improve the PL quantum yield and the spectral resolution. The near-infrared (NIR) fluorescence excitation has attracted much attention because it offers deep tissue penetration and it avoids the autofluorescence of the biological samples. In our study, we have shown both spectral and temporal PL modifications under two-photon excitation of quantum dots (QDs) placed in one-dimensional porous silicon photonic crystal (PhC) microcavities. We have demonstrated an up-to-4.3-fold Purcell enhancement of the radiative relaxation rate under two-photon excitation. The data show that the use of porous silicon PhC microcavities operating in the weak coupling regime permits the enhancement of the PL quantum yield of QDs under two-photon excitation, thus extending the limits of their biosensing applications in the NIR region of the optical spectrum. (C) 2020 Optical Society of America

2021, Dovzhenko, D., Saanchez-Iglesias, A., Grzelczak, M., Rakovich, Y., Krivenkov, V., Kriukova, I., Samokhvalov, P., Nabiev, I., Крюкова, Ирина Сергеевна, Самохвалов, Павел Сергеевич, Набиев, Игорь Руфаилович

© 2021 SPIE.Semiconductor quantum dots (QDs) feature high values of the two-photon absorption (TPA) cross-sections, enabling their applications in biosensing and nonlinear optoelectronics. However, the efficient QD photoluminescence (PL) intensity caused by TPA requires high-intensity laser excitation which hinders these applications. Placing the QDs in the micro- or nanocavities leads to a change in their PL properties. Particularly, near plasmon nanoparticles (open nanocavities) the local field may be enhanced by the localized plasmons, which will lead to an increase of the TPA efficiency. Alternatively, placing QDs in a photonic crystal may boost an increase of their PL quantum yield due to the Purcell effect and also increase their PL intensity at the photonic mode wavelength due to the redistribution of the density of photonic states. In this study, we have fabricated thin-film hybrid materials based on QDs placed near plasmonic nanoparticles or in the photonic crystal. We have demonstrated a 4.3-fold increase of the radiative recombination rate of QDs in the photonic crystal cavity under the two-photon excitation, resulting in the increase of the PL quantum yield. In turn, the coating of the QDs films with the gold nanorods led to the 12-fold increase in TPA at the maximum of the plasmon spectrum. Our results pave the way to a strong increase of the PL efficiency of the QDs under two-photon excitation for their applications in biosensing and nonlinear optoelectronics.

2019, Dovzhenko, D., Vaskan, I., Kriukova, I., Rakovich, Y., Nabiev, I., Крюкова, Ирина Сергеевна, Набиев, Игорь Руфаилович

2019, Mochalov, K., Dovzhenko, D., Vaskan, I., Kryukova, I., Rakovich, Y., Nabiev, I., Крюкова, Ирина Сергеевна, Набиев, Игорь Руфаилович

© 2019 SPIE.Light-matter coupling between the molecular dipole transitions and a confined electromagnetic field provides the ability to control the fundamental properties of coupled matter. The use of tunable optical microcavities for electromagnetic field confinement allows one to affect the coupled state properties in a controllable manner, whereas the coupling strength in this system strongly depends on the transition dipole moment and a mode volume of the cavity. In this study we have demonstrated controllable emission of Rhodamine 6G organic molecules with relatively low and unoriented dipole moments in a strong coupling regime by placing them into a tunable Fabry-Perot microcavity.