Tunable resonant spectra through nanometer niobium grating on silicon nitride membrane

摘要

Transmission characteristics at visible light range in a designed superconducting niobium grating on the silicon nitride membrane have been numerically analyzed based on the finite element method in conjunction with a two-fluid model. The niobium strips are premeditated to possess a trapezoid cross section, giving rise to an extra tuning parameter of top/bottom width. The simulation results clearly reveal that the resonant features of transmittance spectra of the superconducting system can be altered by the spacing, the geometry parameters of the superconducting grating, and the ambient temperature of the system. It is found that the positions of the resonant peaks can be manipulated either by the spacing of the grating or the bottom width of the trapezoid cross section of the superconducting strip or their combinations. In addition, the transmission resonances possess higher quality factors when either decreasing the height and the top width of the trapezoid cross section of the superconducting strip or increasing the temperature close to the critical temperature of the superconductor.