We demonstrate the efficient amplified spontaneous emission (ASE) of rhodamine 640 in asymmetric-coupled-waveguides. In these structures, two active waveguides, one doped with [2-[2-[4-(dimethylamino)phenyl]ethenyl]-6-methyl-4H-pyran-4-ylidene]-propanedinitrile (DCM) and the other with rhodamine 640, are coupled by a passive layer of polyvinyl alcohol. Under a suitable pumping wavelength of 500 nm, the DCM waveguiding layer acts as the donor and rhodamine waveguiding layer acts as the acceptor. Time-resolved fluorescence measurements are employed to confirm that radiative energy transfer is the responsible mechanism for ASE when the waveguiding layers are separated by a thickness of less than 50 nm. In this case, the ASE threshold was found to be reduced by a factor of 16, associated with an intensity enhancement of 56 times, compared to that of the rhodamine waveguiding layer. Next, we investigate the ASE properties of asymmetric-coupled-waveguides as a function of coupling layer thickness. The thickness-dependent coupling constant is simulated using the coupled-mode theory, and its behavior is applied to understand the experimental results.
We demonstrate the role of coupling coefficients in asymmetric coupled waveguides towards delivering a low threshold amplified spontaneous emission (ASE). A theoretical investigation in four different coupled waveguides possessing varying order of symmetry that arises from the bounding media refractive indices shows that the coupling coefficient carries the asymmetry in accordance with the nature of symmetry of the investigating structure. That is, a symmetric coupled waveguide is characterized with identical and asymmetric coupled waveguides, with, unlike coupling coefficients. The effect of unequal coefficients designating the electromagnetic energy transfer from one waveguide to the other and vice versa are experimentally demonstrated on the ASE of the acceptor (Rhodamine 640) by flipping the positions of the donor [[2-[2-[4-(dimethylamino) phenyl] ethenyl]-6-methyl-4H-pyran-4-ylidene]-propanedinitrile (DCM) and acceptor molecules that exist in the opposite waveguides of an asymmetric coupled waveguide. We also correlate the value of the coupling coefficient with the observed threshold of the acceptor ASE towards the optimization of a coupled waveguide as an efficient optical amplifier.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.