Ordering of bicyclic signed digraphs by energy

Let S_n be the class of bicyclic signed digraphs with n vertices whose two signed directed even cycles are vertex-disjoint. In this paper, we characterize the ordering of bicyclic signed digraphs in S_n by energy with two positive or negative directed even cycles (resp., one positive directed even cycle and one negative directed even cycle). Furthermore, we determine extremal energy in S_n by the two orderings.