Applications of Hyperbolic Metamaterial Substrates
Figure 5
A subwavelength emitter such as quantum dot emits light with all spatial frequencies (i.e., wavevectors). (a) The light can couple to propagating waves in vacuum which are reflected and transmitted by a slab (e.g., dielectric) placed in the vicinity of the emitter. (b) If the slab is metallic, another route opens up which corresponds to the coupling of light to surface plasmons. The wavevector of light that couples to the surface plasmon polariton is . (c) The light with large wavevectors emanating from the emitter cannot propagate in vacuum. If the slab is lossy (metal or dielectric), these high- waves are simply absorbed. This is the phenomenon of quenching occurring in the near field of any lossy object. (d) A slab of hyperbolic metamaterial allows the propagation of these high- waves. In the near field, the subwavelength emitter couples most efficiently to the HMM states as compared to plasmons or propagating waves in vacuum. This is due to the availability of a large number of these HMM states.
