Improving the performance of plasmonic nanolasers in the visible region using SLR modes of optimized silver nanocylinder arrays: reducing threshold and enhancing emission

Abstract

Given the light-based technology, it seems inevitable in the future to develop miniature coherent light sources (micro- and nanolasers) with low energy consumption. Metal nanoparticles have a remarkable ability to concentrate light energy at very small dimensions and mode volumes on the nanometer scale, allowing the control and amplification of light on the nanoscale. Meanwhile, by embedding a periodic array of metal nanoparticles in the gain medium, by utilizing plasmonic resonances, and by overcoming the optical loss of the gain medium, one can provide a promising platform for enhanced nanolaser performance. Using the finite-difference time-domain (FDTD) numerical method, this study deals with designs of the nanolaser based on a periodic array of silver (Ag) nanocylinders embedded in a Rhodamine (R6G) gain medium. This study tries to optimize the characteristics of the laser components under different operating conditions, across several consecutive steps, to achieve more effective and efficient performance of the designed laser. Calculations indicate that by means of the Gaussian radiation pumping, and by optimizing both the concentration and the thickness of the gain medium at 80 nm, one can significantly decrease the lasing threshold by minimizing optical losses. Moreover, by keeping the gain medium thickness and concentration constant, one will observe a further decrease in the lasing threshold and an increase in laser emission intensity through adjusting the silver nanocylinder array period and leveraging the strong optical fields of the surface lattice resonance (SLR) mode at a 375 nm period. Furthermore, by optimizing the radius and height of the nanocylinders at 50 nm and 45 nm, respectively, one can achieve a lower lasing threshold at a pump fluence of 1.06 \(\:\text{m}\text{J}\:{\text{c}\text{m}}^{-2}\) through the strong energy coupling between plasmonic modes and gain molecules, with a narrow spectral width. This research can significantly contribute to the design and development of low-lasing threshold plasmonic nanolasers in the visible spectrum, offering higher efficiency for use in optical sensors, photonic circuits, and other plasmonic devices.