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提出了一种由金属光栅和流体光波导结构组成的,基于表面等离子波耦合的光栅耦合器。利用光栅的衍射效应,将金属光栅与介质分界面之间产生的表面等离子波耦合到流体光波导中,并且能够沿着流体光波导稳定地向前传播。通过采用基于有限时域差分算法的FDTD Solutions软件对光栅耦合器进行了参数优化及特性分析,通过优化使该结构在650 nm波长下的耦合效率达到56%。此外,由于该结构对TE偏振光和TM偏振光的选择比达到70∶1,因此具有偏振器的功能。同时由于TE偏振光耦合频谱的频带宽度仅为20 nm,该结构还具有窄带滤波的作用。此外,还研究了光栅结构参数、入射角以及流体折射率对耦合频谱的影响。
A grating coupler based on surface plasmon wave coupling consisting of a metal grating and a fluid optical waveguide structure is proposed. Using the diffraction effect of the grating, a surface plasmon wave generated between the metal grating and the medium interface is coupled into the fluid optical waveguide and can stably propagate forward along the fluid optical waveguide. The grating coupler has been optimized and characterized by using FDTD Solutions software based on the finite difference time-domain algorithm. Through optimization, the coupling efficiency of the grating coupler reaches 56% at 650 nm. In addition, since the structure has a 70: 1 selectivity ratio for TE polarized light and TM polarized light, it has the function of a polarizer. At the same time, as the bandwidth of the TE polarization coupling spectrum is only 20 nm, this structure also has the function of narrowband filtering. In addition, the influence of grating structure parameters, incident angle and fluid refractive index on the coupling spectrum has also been studied.