Hybrid Plasmonic Waveguides For Low Threshold Nanolasers

Due to the diffraction limitation, the size of a dielectric optical cavity of such traditional lasers must be larger than the half wavelength of the optical field in all three dimensions. In order to remove this limitation, surface plasmons can be used. This method has achieved great progress in overcoming the limitation in optics. Nowadays, the main challenge associated with plasmonic cavities is the loss that mainly comes from metal absorption. Realizing both low propagation and high field confinement is very important.In this paper, firstly, we introduce some research about nanolasers and surface plamons. Secondly, we analyze the property of surface plasmons and numerical methods in computational electromagnetics.We propose and compare five kinds of models by maintaining modes in a hybrid plasmonic waveguide under different geometric shapes and parameters of models. Here we use the Comsol Multiphysics software to investigate the properties by the finite element method. Scattering boundary condition and convergence tests are used to ensure the solution accuracy. We analyze the effect of the geometric shape and parameters on modal properties and lasing threshold. The modal effective index, effective propagation loss, normalized mode area and confinement factor can reflect the modal properties. We find that most of the optical energy is concentrated within the gap and the theoretical threshold can be reduced by decreasing both the gap width and the corner radius of the metal films. The structure could be realized using a relatively simple fabrication process and would be useful for further active plasmonic circuits.