Diffusion-inspired time-varying phosphorescent decay in a nanostructured environment

Abstract

Structured environment controls dynamics of light-matter interaction processes via modified local density of electromagnetic states. In typical scenarios, where nanosecond-scale fluorescent processes are involved, mechanical conformational changes of the environment during the interaction processes can be safely neglected. However, slow decaying phosphorescent complexes (e.g. lanthanides) can efficiently sense micro-and millisecond scale motion via near-field interactions. As the result, lifetime statistics can inherit information about nano-scale mechanical motion. Here we study light-matter interaction dynamics of phosphorescent dyes, diffusing in a proximity of a plasmonic nanoantenna. The interplay between the time-varying Purcell enhancement and stochastic motion of molecules is considered via a modified diffusion equation, and collective decay phenomena is analysed. Fluid properties, such as local temperature and diffusion coefficient are mapped on phosphorescent lifetime distribution extracted with the help of inverse Laplace transformation. The presented photonic platform enables contactless all-optical thermometry and diffusion measurements paving a way for a plethora of possible applications. In particular, the proposed analysis can be used for detailed studies of nanofluidic processes in lab-on-a-chip devices, which are extremely hard or even impossible to analyse with other optical methods.

Memory effects in scattering from accelerating bodies

“…The investigated memory effect is universal and can emerge in many wave-related disciplines and scenarios, e.g., optical, where molecules and even macroscopic structures are being rotated with laser beams [40][41][42][43][44] and optofluidics, where timedependent Purcell enhancements can emerge, 45,46 in radar, LIDAR, and sonar, where the micro-Doppler signatures produced by rotating blades of a helicopter are of interest, 34,47,48 and, even in astronomy, where neutron stars can be approximated by rotating dipoles. 49 Although the effects of rotation on scattering were comprehensively studied in the past (e.g., Refs.…”

Reflection of the individual multipoles fields from a flat substrate in the angular spectrum approach

“…Modern requirements for nanophotonic devices imply miniaturization and integration. Such areas of nanophotonics as lab-on-a-chip [1][2][3][4][5], photonic computing [6,7], metamaterials [8][9][10] and metasurfaces [11], and others are developing at a high rate. At the stage of design there it is often necessary to know the complexity of the optical near fields spatial distribution [12].…”