Design of coupler in the near infrared incident wavelength by COMSOL

Surface plasmon polariton (SPP) are waves that propagate along the metal-dielectric interface with exponentially decaying electromagnetic fields in both sides of the media. The strip surface plasmon waveguide has long been considered a useful device to achieve highly integrated optics. Analysis of SPP excitation and propagation characteristics in the waveguide by relying on a classic model, namely, Drude was presented. This research is conducted from visible light to near infrared incident wavelength. Strip SPP metal waveguide mode field distribution was studied. Results show that when the thickness of the metal remains constant and its width increases, the electromagnetic field distribution becomes increasingly concentrated in both sides of the strips. When the width of the strip is unchanged, thickness increases and the electromagnetic field distribution becomes increasingly focused on the metal inside. A long incident wavelength means that the concentration of metal strip around the electric field is small. Long incident wavelength can also lead to inter-channel interference. That is, having a large wavelength means one must select a wide strip waveguide. This study, which is about spontaneous radiation characteristics from 840 nm to 910 nm strip waveguide, reveals that a small part of radiation is evanescent to the metal area in the surface plasmon evanescent radiation patterns. Application design and analysis indicate that complete transfer of energy only occurs once in the limited transmission distance of the strip SPP waveguide. When the wavelength is long, the concentration field is reduced and coupling is reinforced. The designed coupler can realize optical WDM in 1 310 and 1 550 nm.