  We used two-dimensional Finte-Difference-Time-Domain (FDTD) software to study
the transition behavior of nano-particles from scatterers to an optically
uniform medium. We measured the transmission efficiency of the dipole source,
which is located in the high refractive index medium(index=2.00) and
encapsulated by low index resin(index=1.41). In an effort to compose
index-matched resin and to reduce internal reflection, high-index
nano-particles are added to low-index resin in simulations of various sizes and
densities. As the size of the nano-particles and the average spacing between
particles are reduced to 0.02 lambda and 0.07 lambda respectively, the
transmission efficiency improves two-fold compared to that without
nanoparticles. The numerical results can be used to understand the optical
behavior of nano-particles and to improve the extraction efficiency of high
brightness light-emitting-diodes(LEDs), through the use of nano-composite
encapsulant.
