Increasing the electric field amplification in the metal-insulator-metal structure with a grating hybrid of bowtie nanotriangle and cylindrical nanodisc

Abstract

In this paper, the strong electromagnetic coupling between an integrated grating of an array of periodic gold nanodiscs and an array of bowtie nanotriangles placed on layers of a dielectric and a metal has been investigated. The upper layer is periodically created by removing each nanodisk in the array of nanodisks and replacing it with bowtie nanotriangles. The structure for near field radiation with linear polarization at 800 nm wavelength is optimized so that it has the highest amount of amplification in the gap space between the tips of the nanotriangle with a minimum value of 188 times and a maximum of 320 times. The simulation results confirm that the huge field enhancement obtained is due to the strong coupling between the LSPR formed in the grating of bowties nano triangle and nanodiscs and the SPPs formed in the metal film. The amount of amplification compared to the array of only nanodiscs (about 32 times) or only bowtie nano triangles (about 120 times) is not only higher, but also the anti-crossing behavior is observed. The high amplification obtained at the mentioned wavelength can be used for laser oscillators with a central wavelength of 800 nm, such as titanium sapphire, etc., which has many applications in near-field physics, SERS, and ultrafast lasers.