基于SPP的1550纳米光波导的超长传输特性

The characteristics of long-range propagation for SPP waveguide excited by a 1550nm light

采用严格电磁理论研究了介质-金属-介质型光波导激发表面等离子激元(SPPs)的电磁特性,对比分析了SPP波在SiO2/Ag/SiO2和Si/Ag/Si光波导的传输距离。研究表明,对于1550nm光通信波长入射光及10nm厚的金属银膜层,SiO2/Ag/SiO2光波导中非对称SPP的传输距离可达40cm,明显高于对称SPP波的传输距离,也显著高于非对称SPP波在Si/Ag/Si波导中的传输距离,具有超长传输距离;随着金属层厚度的增加SPP波的传输距离明显减小,当银层厚度超过50nm后,非对称的SPP在SiO2/Ag/SiO2及Si/Ag/Si波导中的传输距离趋于一致,约为200nm;此时银层厚度变化对SPP波传输距离的影响明显减弱。

A numerical analysis of surface plasmon waveguides exhibiting both long-range propagation and spatial confinement of light with lateral dimensions is presented. Attention is given to characterizing the dispersion relations, wavelength-dependent propagation, and energy density decay in two-dimensional dielectric-metal-dielectric structures. It is shows that if the thickness of the metal film is sufficiently small, the metal adjacent to the upper and lower interfaces with the dielectric at the excitation of the surface plasmon polariton（SPPs） will produce coupled and split into symmetrical and anti-symmetrical SPP. The transmission distance of the anti-symmetric mode in SiO2/Ag/SiO2 waveguide is up to - 400 mm for incident light of 1550nm and the metal film thickness of 10nm. The transmission distance in the Si/Ag/Si waveguide is only - 9.2mm, which much lower than the transmission distance in SiO2/Ag/SiO2 waveguide. With the increase of the metal film thickness, the transmission distance of SPP significantly reduced. When the metal film is thicker than 50nm, the transmission distance is about 200nm for the anti-symmetry of SPP in SiO2/Ag/SiO2 and Si/Ag/Si waveguides. For a anti-ymmetric mode, this is the opposite trend. Symmetric and anti-symmetric SPP mode decays exponentially along the vertical interface of the dielectric layer. The attenuation distances of the symmetrical and anti-symmetrical SPP in the Si are approximately 400nm and 500nm, respectively. And the attenuation distances in the SiO2 is about 2μm and 3μm, which much larger than the distances in the Si.