  A set of grating couplers that convert plane waves into odd pairs of plasmons
supported by extremely thin layers of doped indium tin oxide is designed. The
inverse design approach is implemented to improve the efficiency of ordinary
periodical couplers significantly. The optimization code based on the gradient
descent method and direct Maxwell solver is designed in Matlab. Three models
with different optimization levels are compared and discussed. The results of
calculations are prepared for subsequent experimental verification. Considered
odd plasmonic pairs represent an example of high quality modes tunable using a
field effect. They are potentially applicable for the implementation in various
active electro-optical devices and lead the way to fully semiconductor based
plasmonics.
