Analysis of Optical Resonator with Waveguide Discontinuities Constructed by Two-Dimensional MDM Plasmonic Waveguide

An optical resonator with two waveguide discontinuities constructed by a metal-dielectric-metal plasmonic waveguide has been analyzed using the finite-difference time-domain (FD-TD) method with the piecewise linear recursive convolution (PLRC) method. The waveguide discontinuity has been expressed as an equivalent transmission line circuit whose circuit parameters are estimated from the reflection coefficients analyzed by the FD-TD method. We have confirmed the validity of the circuit configuration because the reflection characteristics of the equivalent circuit with the circuit parameters agree with those of the FD-TD method. Next, we have analyzed a resonator structure with two waveguide discontinuities and shown that the equivalent circuit gives a good approximation for the structure with a large difference in waveguide width at the discontinuities, in which conventional equivalent circuits had large errors.