Efficient sensitivity analysis of surface plasmon waveguide structures

We propose a novel approach for efficient sensitivity analysis and design optimization of surface plasmon polaritons (SPPs) based waveguide structures. This approach has been utilized to analyze and propose novel designs of different structures. It has been exploited to design a novel SPP waveguide using a metal loaded on silicon on insulator (SOI) for subwavelength applications. In this design, the SOI material is utilized due to its wide application in electronic circuits. It also allows for strong guiding and hence subwavelength light confinement. The utilized metal is gold (Au) at a wavelength of 1.55 μm. The effect of the different design parameters of this structure on the propagation length of the fundamental TM mode is efficiently studied using the proposed approach. The imaginary distance 3D ADI BPM is utilized to calculate the propagation length. The sensitivity information is then estimated using the adjoint variable method without any additional simulations. The same approach is utilized to propose an optimized design of new 1x3 SPP power splitter/combiner using metal on insulator. In this design the multimode interference phenomenon is utilized. Our goal is to minimize the insertion loss for practical applications. The optimized design has a low insertion loss of 1.5 dB and compact size.