SEARCH · Engineering Papers

Results for “Optical microcavities”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

39 records · Page 3

All sources NASA NTRS DOE OSTI

DOE OSTI2023

Multidimensional Coherent Spectroscopy of Molecular Polaritons: Langevin Approach

We present a microscopic theory for nonlinear optical spectroscopy of N molecules in an optical cavity. Using the Heisenberg-Langevin equation, an analytical expression is derived for the time- and frequency-resolved signals accounting for arbitrary numbers of vibrational excitations. We identify clear signatures of the polariton-polaron interaction from multidimensional projections of the signal, e.g., pathways and timescales. Cooperative dynamics of cavity polaritons against intramolecular vibrations is revealed, along with a crosstalk between long-range coherence and vibronic coupling that may lead to localization effects. Our results further characterize the polaritonic coherence and the population transfer that is slower.

74 ATOMIC AND MOLECULAR PHYSICS↗

DOE OSTI2023

Aggregation‐Induced Stimulated Emission of 100% Dye Microspheres

Dyes with aggregation-induced emission (AIE) properties have gained interest due to their bright luminescence in solid-state aggregates. While fluorescence from AIE dyes is widely exploited, relatively little is known about aggregation-induced stimulated emission. Here, stimulated emission of tetraphenylethene (TPE)-based organoboron AIE dyes, TPEQBN, in thin films and in microcavity lasers is investigated. Using femtosecond pump–probe spectroscopy, gain coefficients up to 230 cm -1 at 500 nm are measured. Using rate equations, concentration- and pump-dependent gain dynamics as well as laser build-up dynamics are analyzed. During laser oscillation, radiative stimulated emission allows high instantaneous quantum yield greater than 90% to be achieved. Solid-state microspheres made of 100% AIE dyes are fabricated via microfluidic emulsion and solvent evaporation method. Coupled with high gain and high refractive index of 1.76, microspheres as small as 2 µm in diameter show lasing by nanosecond pumping with a threshold of ≈10 pJ µm –2 . Polymer coated, but not bare, microspheres are internalized by live cells and generate narrowband cavity-mode emission from within the cytoplasm. This work shows the potential of AIE dyes as laser materials.

36 MATERIALS SCIENCE↗

DOE OSTI2019

Ultrastrong coupling of vibrationally dressed organic Frenkel excitons with Bloch surface waves in a one-sided all-dielectric structure

We demonstrate a transition from weak, to strong, to ultrastrong coupling of Frenkel molecular excitons and Bloch surface wave photons at room temperature using a one-sided, all-dielectric optical structure. The all-dielectric structure comprises an organic semiconductor thin film on the surface of a distributed Bragg reflector. We investigate the evolution of multiple vibronic polariton branches and their dominant absorption peaks as a function of coupling and in-plane momentum, which is absent in previous ultrastrong coupling systems. Measurements are interpreted using both the transfer matrix method and a coupled-oscillator model without the rotating wave approximation. The dependence of Rabi splitting on the number of excitons and electrical field amplitude is also modeled showing a transition to ultrastrong coupling at film thicknesses ≥ 50 nm. Furthermore, this low-loss polaritonic structure enables us to study phenomena such as organic exciton-polariton dynamics, ultralong range polariton propagation, and high efficiency energy transport in the ultrastrong coupling regime at room temperature.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗