Fig. 5.

Calculated plots of the transmission efficiency $\eta$ on the curvature radius $R$ (see Fig. 4). The values of the variable model parameters are: $\rho =10\mathrm{nm}$, (1) $r_0=5\rho$, (2) $r_0=10\rho$, (3) $r_0=15\rho$, and (4) $r_0=20\rho$.