近红外波长下COMSOL软件实现新型耦合器的设计

一直以来条状表面等离子波导被认为是实现高集成光路的有效器件,首先采用经典的Drude模型对条状波导中SPP激发与传播特性完成了分析。针对可见光到近红外入射波长的条件完成了条状SPP波导的模场分布的研究,得出,当金属的厚度不变宽度越大,电磁场分布就越集中在条状波导的两侧;当金属条状的宽度不变,厚度越大时电磁场分布会越集中在金属内;入射波长越长会使得金属条状周围电场的集中越小,且还会导致信道间的干扰。利用得到的条状波导特性进而设计了一种新型的耦合器,器件设计结果表明:条状SPP波导在有限传输距离上能量完全转移只发生一次;波长较长时,场的集中度减小,耦合增强;条状SPP波导耦合器可以实现1310 nm和1550 nm的光波分复用。这一研究对光子器件的发展有一定的理论和实际意义。

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.