One means of controlling the color, brightness, and directional profile of light emitted from LEDs or luminescent materials, in general, is through the use of nanostructures. Metallic films and structures are a particular class of material that have been of considerable interest for this purpose in recent times. In this talk, we consider the lifetime and efficiency of a phosphor layer situated near a metallic film.

We will first make general observations of the effects of the plasmons on the lifetime and quantum efficiency of the activator ions in the phosphor and on the role of the plasmons in the emission process. The effect of the plasmons in the excitation process and on the total luminescence from the system will also be discussed.

Finally, an expression for the lifetime of the optical ions interacting with the surface plasmon modes will be derived using the relevant Einstein A and B coefficient. This requires a determination of the mode density of the surface plasmons. Since the surface plasmons represent a 2-dimensional system, a length parameter must be introduced in order to calculate the mode density. We derive this parameter using a semi-classical approach, and show its dependence on the dielectric constants of the system and on the distance from the metallic layer.