Spontaneous Emergence of Periodic Patterns in a Biologically Inspired Simulation of Photonic Structures

We simulate an evolutionary process in the lab for designing a novel high confinement photonic structure, starting with a set of completely random patterns, with no insight on the initial geometrical pattern. We show a spontaneous emergence of periodical patterns as well as previously unseen high confinement subwavelength bowtie regions. The evolved structure has a $Q$ of 300 and an ultrasmall modal volume of $0.112(\lambda /2n{)}^3$. The emergence of the periodic patterns in the structure indicates that periodicity is a principal condition for effective control of the distribution of light.

Figure 1

Evolution of resonator (black: high index, white: low index). (a) Random starting region, (b) disturbed Bragg reflector (DBR) layers begin to form, (c) DBR layers begin to emerge, (d) DBR layers are clearly defined.

Figure 2

Normalized field amplitude of optical mode in an evolved resonator (5000th generation). The inset shows that most of the field is localized in the center slot.

Figure 3

Propagation eigenmodes. (a) Field localization, normal to the interface. (b) Field localization, tangent to the interface.

Figure 4

Performance of the EA and a random search compared.