Optics of an individual organic molecular mesowire waveguide: directional light emission and anomalous refractive index. (5th April 2016)

• Record Type: Journal Article
• Authors: Tripathi, Ravi P N; Dasgupta, Arindam; Chikkaraddy, Rohit; Patra, Partha Pratim; Vasista, Adarsh B; Kumar, G V Pavan
• Is Part Of: Journal of optics. Volume 18:Number 6(2016:Jun.)
• Publication Date: 2016-04-05
• Subjects: organic photonics -- Fourier microscopy -- optical antenna -- waveguiding; trup-Hansen J -- Simbrunner C -- and Rubahn H -- 2013 -- Organic surface-grown nanowires for functional devices -- Reports on Progress in Physics; Optics -- Periodicals; 535.05
• DOI: 10.1088/2040-8978/18/6/065002
• Languages: English
• ISSNs: 2040-8978

Abstract

Abstract: We report on experimental investigations performed on an isolated organic mesowire waveguide resting on a glass substrate. The waveguide was made of diaminoanthraquinone (DAAQ) molecular aggregates. First, we show directional emission of light from distal ends of the DAAQ waveguide. For a given mesowire geometry, operating in passive or photoluminescence regimes, we quantified the emission angles by combining multi-wavelength Fourier-plane optical microscopy and photoluminescence micro-spectroscopy. We found light emission in the photoluminescence regime to be more directional in nature compared to the passive waveguiding regime, which was supported by three-dimensional finite-difference time-domain (FDTD) simulations. Second, we measured the anomalous behaviour of refractive index as a function of emission wavelength using the spectra of directionally emitted light. Third, by using spatial-filtered collection optics, we observed and quantified single-excitation dual-channel directional, active emission from DAAQ mesowire. The results discussed herein has implication not only in understanding some fundamental aspects of exciton-polariton mediated directional light emission, but also in applications such as organic optical antennas and photonic couplers.