Figure 2.

Comparison of coupling strength, ln|r_p|², of LRSPP and SRSPP in the case where n₀ = n₁ and d₁ = 0 nm considered as pure plasmonic modes for (a) n₀ = n₁ = 1.29; (b) n₀ = n₁ = 1.33 and n₀ = n₁ = 1.3616. Other parameters are λ = 633 nm, n₂ = 0.18344 + 3.4332i and n₃ = 1.33; (d) Normalized attenuation coefficients $k_{sp}^{"}/k_{free-space}$ for the cases in (a–c). The solid red curves in (a–c) were the solutions to Equation (2) for LRSPP mode and the dashed red curves are the solutions for SRSPP mode.