Three-dimensional Light Confinement Design In Hybrid Surface Plasmonic Nanolaser

Surface plasmon polariton(SPP), a kind of surface electromagnetic wave, is formed by the energy exchange between incident photon and electronic in metal, such as gold and silver and propagates along the metal surface in the form of electron oscillation waves. Surface plasmon amplification by stimulated emission of radiation(SPASER) based on SPP mode is the major content of this research. Our nanolaser design is based on the SPPs model object. Hybrid surface plasmon(HSP), the combination of dielectric nanowire and SPPs, possesses low transmission loss of dielectric nanowire, enhancement medium and light filed confinement in SPPs. Since the advantages in low-loss, high light-matter interaction of the hybrid surface plasmon waveguide mode, SPASER based on HSP waveguide have gained in-depth and widely research attention. However, the traditional SPASER tended to emphasize light confinement within the two-dimensional plane. But there are no studies about the light confinement on the third dimension. So there is suffering on further improving the light-matter interaction and forming quantum light source in nanoscale. Faced with this challenge, our research started from enhancing the capacity of nano-laser light field confinement, surface plasmon nano-lasers with the ability of all three-dimensional light field confinement has been designed. Wherein the optical resonator is Fabry-Perot cavity based on CdS nanowires. Our research innovatively introduces the parity-time symmetry principle into traditional HSP cavity. We analyze the mechanism of how to increase a third dimension of the light field confinement after PT symmetry principle generating. Starting from the calculated analysis of coupled-mode theory, we constructed the third dimension of light field confinement in the HSP waveguide successfully. We used the finite element analysis method simulation software COMSOL Multiphysics. We build numerical simulation model strictly with features consist of material equivalent refractive index, three dimensional light distribution with different gain loss conditions, field energy value and effective model volume(Veff). All these work verify that the three-dimensional light field confinement capacity exist. Purcell factor, an important parameter in the light and matter interaction, can be simply understood as the ratio between quality(Q) factor and the effective mode volume. The effective mode volume has been reduced to a level of 0.00169 μm3 and it may continue to decrease. the study has important significance in micro- nano-optic and cavity quantum electrodynamics. Effective mode volume has been reduced by 5 times. It means a big breaking of the device limit.