Impedance matching via ultrathin metatronic layer assisted by Smith Chart.

Metatronics, as a feasible paradigm of nanocircuits using effective electronic elements (e.g., nanocapacitors, nanoinductors, and nanoresistors), provides the possibility for light manipulation in subwavelength scales assisted by the circuit-related technologies in electronics. As a representative technique in electronics, Smith Chart provides a fast, less-computation and graphical approach to solve the problems related to impedance matching. Here, we transplant the Smith Chart into the paradigm of optical metatronics to develop an analytical approach for impedance matching for light propagation and coined the name of graphical metatronics. In this approach, the impedance characteristics of four basic types of ultrathin metatronic layers are creatively mapped into each rotation trace on the complex Γ mathematical plane (Γ means the reflection coefficient). The impedance matching problems can be graphically solved by searching for feasible rotation traces on the Γ plane without full-wave simulations. Based on this approach, various applications related to impedance matching (e.g., antireflection coating, perfect transmission, absorber, etc.) are developed analytically and validated by numerical results. The proposed approach constructs the bridge among Smith Chart, plasmonics and photonics, providing a fast, visualized and less-computation route and guideline to develop various nanophotonic structures and devices for impedance-matching applications.