Second harmonic double resonance cones in dispersive hyperbolic metamaterials

We study the formation of second harmonic double-resonance cones in hyperbolic metamaterials. An electric dipole on the surface of the structure induces second harmonic light to propagate into two distinct volume plasmon-polariton channels: A signal that propagates within its own peculiar resonance cone; and a phase-locked signal that is trapped under the pump's resonance cone. Metamaterial dispersion and birefringence induce a large angular divergence between the two volume plasmon-polaritons, making these structures ideal for subwavelength second and higher harmonic imaging microscopy.