The field of nanophotonics has had numerous great achievements in the past few years. The scaling down of optical devices has created a need for active, light emitting materials whose properties need to be controlled for usage at such small scales. This dissertation presents results on the control of the emission of different light emitting materials. Chapter one presents a brief discussion of active materials for on-chip applications, what they are and their uses.

Chapter two deals with the enhancement of CdSe quantum dots embedded in a microcavity. After a brief overview of the density of photon modes and how enhancement can be achieved, the experimental details and results are presented, showing enhancement of the photoluminescence of the quantum dots by a factor of 2.7.

The third chapter discusses experiments with CdSe dots and resonant energy transfer. This effect involves a donor and an acceptor in close proximity, with the former "giving" its energy to the latter. The emission of the acceptor is further enhanced by making use of a microcavity, with a total enhancement by a factor of 13.

Experimental results on rare earth doped GaN in the form of a powder are presented in chapter four. This type of material presents highly luminescent properties, and offers the flexibility of being used in a hybrid manner (on silicon for example). Cathodoluminescence, photoluminescence and lifetime properties of various concentrations of RE dopants are discussed and presented, as well as a visible waveguide application of Eu doped GaN powder. Two temperature-sensitive changes in the lifetime behavior of Eu doped GaN occur at 104 and 195 K. The lifetime dynamics are studied in greater detail using a model with corresponding rate equations.

The last chapter shows applications of another class of a light emitting material: silica clad organic dyes. These particles have a promising future in applications such as labeling and sensing.

Even though the materials studied here emit light in the visible portion of the spectrum, all of the experiments herein contained can be realized with their infrared counterparts.