Control of led emission via surface plasmon interaction
Harries, Michael David
In this thesis we demonstrate how the optical emission from a typical light emitting diode (LED) device can be spatially controlled via the deposition of a periodically structured gold film. A periodically structured gold film was deposited within a 20 um square aperture in the top, p-doped, contact surface of an AlGaInP/GaInP multiple quantum well edge emitting LED. We show that the far-field emission is vastly altered and is spatially controlled by the properties local to the surface plasmon. It is shown that each order of rotational symmetry produces a single emission curve in the far-field which is related directly to the coupling of photon to surface plasmon via the grating vector. We find that the origin of these strong emission curves in the far field is emission of the surface plasmon as photons. These are highly polarised and have a peak emission of 660 nm (as opposed to the peak wavelength from the standard LED device of 654 nm). The k vector for the surface plasmon propagating within the thin gold film with SiO<sub>2</sub> islands is found to be 1.002x10<super> 7</super> m"1 from experimental measurement. It is also shown that a similar gold film with a grating of 592 nm would result in normal emission. Considering the surface plasmon emission as being analogous to emission from a linear dipole antenna array, the far-field emission as a function of angle is modelled using Matlab. From comparison with real profile plots this suggests that a surface plasmon wave spans a distance of 7.5 nm which agrees approximately with the propagation length of a surface plasmon in this gold film.
views in local repository
downloads in local repository
The information is available from the following content providers: