The Importance of Being Aperiodic

Thermal Emission Control via Bandgap Engineering in Aperiodically Designed Nanophotonic Devices

“…In the case of the Fibonacci coating ( Figure 3 b) a characteristic trifurcation splitting can be clearly appreciated around a number of frequencies, and one finds a strong emittance within the spectral range corresponding to the midgap in the periodic case. In fact, the presence of allowed bands in certain forbidden regions of the periodic system is a characteristic feature of quasiperiodic systems [ 3 , 4 , 5 , 6 , 7 ]. An analogous pattern is observed in the thermal spectrum corresponding to the Thue-Morse thin film, whereas that corresponding to the period-doubling sequence is more similar to the periodic one around the ω/ω 0 = 1 spectral range.…”

“…Though the recourse to periodic order is quite convenient for the sake of simplicity, during the last decade it has been progressively realized that ordered structures can be suitably expanded to embrace not only periodic arrangements but aperiodic ones as well. In this way, the very notion of aperiodic order, that is, order without periodicity, has been explored to properly describe a growing number of physical systems, including metallic and dielectric multilayers [ 3 , 4 , 5 , 6 , 7 , 8 ]. Thus, well-known materials still remain in use, along with the previously gained technological expertise, as the attention is entirely focused on the (relatively low-cost) aspects related to device architecture optimization.…”

“…The existence of more frequencies for operation becomes particularly useful when looking for selective enhancement (suppression) of thermal emission for some selected frequencies. Thus, by properly exploiting the additional degrees of freedom inherent to the aperiodic arrangements, one can design optical devices offering a broader and more flexible design capability than their periodic counterparts for certain specific applications [ 3 , 4 , 5 , 6 , 7 ].…”

On the Nature of Electronic Wave Functions in One-Dimensional Self-Similar and Quasiperiodic Systems

“…Consequently, light transmission through aperiodic media has deserved an ever-increasing attention in order to understand the interplay between optical properties and the underlying aperiodic order of the substrate [18,[68][69][70][71]. To this end, the mathematical analogy between Schrödinger equation (5) and Helmholtz equation describing a monochromatic electromagnetic wave of frequency propagating in a lossless, dispersionless medium with a variable refractive index profile ( )…”