Figure 3.

Transmissions for the cases of (a) the symmetric structure with the left and right metal cores located at the center of the corresponding cavity, i.e., d = 0; and the asymmetric structure with the left and the right metal cores respectively deviating along +y and −y-axis direction, but with the same deviation distance of d; (b) d = 10, 20, and 30 nm; (c) d = 35, 40, and 45 nm; (d) d = 50, 55, and 60 nm; (e) d = 65, 70, and 75 nm; and (f) d = 80, 85, and 90 nm.