Polarization-controlled dual-wavelength modulator utilizing plasmonic Ag@Au nanorod tetramer arrays

Surface plasmon polaritons (SPPs) can overcome the diffraction limit of traditional optical devices and hold the potential to break through the bottleneck of integration density in conventional components. Herein, a plasmonic modulator controlled by dual wavelengths is designed using a Ag@Au nanorod tetramer array structure based on SPPs. Effective control at different wavelengths is achieved primarily by altering the polarization direction of the incident light, which changes the coupling mechanisms and resonance modes of the SPPs. This work provides an in-depth investigation into the influence of key structural parameters on the modulator’s performance. The plasmonic modulator exhibits high-performance across the conventional (C) band, centered on 1.55 µm. At λ 1 =1.55µm and λ 2 =1.64µm, the device achieves extinction ratios (ER) of 15.414 and 10.917 dB, insertion losses (IL) of 0.26 and 0.57 dB, and modulation depths (MD) of 97.125% and 91.903%, respectively. These results underscore its potential for miniaturized nanophotonic modulation applications utilizing SPP.