D irectional control over the excitation energy transfer between different nanosystems is of critical importance for the emerging field of nanophotonics and has various prospective applications ranging from biological detections to quantum information processing. 1Ϫ14 For instance, the excitation energy transfer between semiconductor quantum dots (QDs) is employed to demonstrate quantum operations, 4 and the stimulated interactions between active optical dipoles and surface plasmons are used to generate plasmonic lasing. 5Ϫ8 Comparing with nonradiative energy transfer (such as Dexter and Fö rster processes), 15,16 radiative energy transfer has sufficient distance range but poor efficiency and directionality. The surface plasmons of the exquisitely designing and optimizing metal nanostructures are powerful tools to enhance the efficiency of both radiative and nonradiative energy transfers. 1,17Ϫ19 The Ag films have been used by Andrew et al. to first demonstrate plasmon-mediated radiative energy transfer from donor to acceptor dye molecules over distances longer than 100 nm, 1 which proceeds in three processes, converting optical dipole of the donors to the surface plasmon on one interface of a Ag film, then cross coupling of two surface plasmons on the opposite interfaces of the film, and finally transferring excitation energy to the acceptors on the opposite side. On the basis of this principle, the corrugated nanostructures have been used by Feng et al. to enhance the cross coupling of the two surface plasmons on the opposite interfaces. 17 A two-dimensional (2D) standing metal nanowire array could be a good candidate to assist radiative energy transfer due to its near-field coupling and imaging behaviors. 20,21 The excitation energy of nanoemitters can be efficiently converted to the surface plasmons through strong coupling near the tips of the Ag nanowires, 10 and the corresponding Purcell factor, P (the ratio of the spontaneous emission rate into the plasmon modes over emission into other channels), is predicted to be as high as 10 3 . 22,23 Metal nanorods support both longitudinal and transverse surface plasmon resonances (abbreviated by LSPRs and TSPRs, respectively) by the free electrons near the metal surface oscillating perpendicularly to and along the long axis of the nanorods. Resonant transmission through a Au nanorod array with a far-field excitation is reported by Lyvers et al.,24 which is found to be caused by the half-