  We theoretically investigate the plasmonic coupling in heterogenous Al-Ag
nanorod dimer. A pronounced Fano dip is found in the extinction spectrum
produced by the destructive interference between the bright dipole mode from a
short Al nanorod and the dark quadrupole mode from a long Ag nanorod nearby.
This Fano resonance can be widely tuned in both wavelength and amplitude by
varying the rod dimensions, the separation distance and the local dielectric
environment. The Al-Ag heterogeneous nanorod dimer shows a high sensitivity to
the surrounding environment with a local surface plasmon resonance figure of
merit of 7.0, which enables its promising applications in plasmonic sensing and
detection.
