Characteristic Analysis of Low-Threshold Plasmonic Lasers Using Ag Nanoparticles With Various Shapes Using Photochemical Synthesis

The characteristics of plasmonic lasers using Ag nanoparticles (AgNPs) with various shapes as cores and gain material doped dielectric medium as shell are analyzed using the finite-element method. We can synthesize spherical, decahedral, flaky hexagonal, and flaky triangular AgNPs in a photochemical process, which induce local surface plasmon resonances at different wavelengths. We analyzed the absorption and scattering characteristics of these AgNPs coated with gain material doped dielectric medium with a given gain coefficient as plasmonic lasers. Numerical results show that compared to conventional spherical AgNPs, AgNPs with sharp corners provide a much lower threshold for plasmonic laser applications. Flaky triangular AgNP is the optimum choice as a resonant core for plasmonic lasers, with the lowest threshold (0.0116) and a relatively narrow linewidth (~0.111 nm). Then, we analyzed the influence of structural parameters on lasing performance using a flaky triangular AgNP as the core of the core-shell plasmonic laser. Changing the size of the core, the thickness of the shell, the refractive index of the dielectric medium, or the radius of the rounded corner for AgNPs regulate the resonant wavelength. Using smaller flaky triangular AgNP as the core and gain material doped silica, refractive index 1.5, as the shell reduced the threshold of the plasmonic laser. In addition, a thermal analysis was also carried out to study the effect of enhanced local fields on the performance of the plasmonic lasers.