ABSTRACT
In this paper, a design for a 1 × 4 optical power splitter based on the multimode interference (MMI) coupler in a silicon (Si)-gallium nitride (GaN) slot waveguide structure is presented-to our knowledge, for the first time. Si and GaN were found as suitable materials for the slot waveguide structure. Numerical optimizations were carried out on the device parameters using the full vectorial-beam propagation method (FV-BPM). Simulation results show that the proposed device can be useful to divide optical signal energy uniformly in the C-band range (1530-1565 nm) into four output ports with low insertion losses (0.07 dB).
ABSTRACT
Utilizing the localized surface plasmon resonance (LSPR) effect of metallic nanoparticles enables their usage as contrast agents in a variety of applications for medical diagnostics and treatment. Those applications can use both the very strong absorption and scattering properties of the metallic nanoparticle due to their LSPR effects. There are certain applications where domination of the scattering over absorption or vice versa would be an advantage. However, the scattering and absorption resonance peaks have practically the same spectral location for solid noble metal nanoparticles at a certain domination of one over the other. In this paper we present gold nanoparticles coated with silicon that switches the order between the scattering and the absorption magnitude at the resonance peak by up to 34% in scattering-absorption ratio and tune the plasmon resonance over the spectrum by up to 56nm. This is obtained by modifying the refractive index of the silicon coating of the nanoparticle by illuminating it with a pumping light due to the plasma dispersion effect in silicon.
