Novel ridge-type gold film waveguide for surface plasmon polariton laser

© 2018, Springer Science+Business Media, LLC, part of Springer Nature. Surface plasmon polariton lasers are the basis for photonic circuits, but their losses, thresholds, and some other problems remain thorny issues. In this study, we put forward a novel ridge-type gold film surface plasmon polariton laser. The device adopts a multi-layer hybrid waveguide structure, where the bottom layer is a gold film, and a gold ridge is formed over the center of the gold film. We symmetrically place the two SiO2layers on both sides of the gold ridge as buffer layers and deposit a gold nanoribbon on the top of gold ridge. Two air gaps are formed between the gold ridge and SiO2buffer layers. We numerically study the structure, and the results show that at the operating wavelength of 1550 nm, the effective mode area reaches 1.375 × 10−5λ2 , and the confinement factor reaches 0.75. When the width of the SiO2layer is 2 nm, the height of the ridge is 10 nm, and the angle of the ridge is 80°, the waveguide can effectively enhance the light field confinement so as to limit the energy to a very small range and exhibits the minimum gain threshold. The waveguide can provide a solution for the optical source device of the surface plasma excitation circuits and has great application potential in the ultra-small and high-density optical chips.