Improving emission in nanorod arrays using quasi-aperiodic inverse design (Presentation Recording)

Photonic structure plays a significant role in determining the brightness and efficiency of nanoemitter systems. Using photonic crystal slabs it is possible to affect these quantities in various ways. First, positioning a leaky mode near the emission frequency allows more light to be extracted from within the slab. Second, concentrating high electric field intensity near emitter locations significantly enhances the spontaneous emission rate. However, a large body of work has suggested these two contributing factors are in competition, making it difficult to simultaneously achieve high electric field intensity and light extraction. In previous work, we identified one mode in an array of GaN nanorods which exhibited a 25X enhancement in extracted power, relative to a uniform slab. However, the mode was uncoupled to normal radiation and, consequently, produced a sharp dip in extraction efficiency. Here, we improve upon the previous design by investigating a new class of quasi-aperiodic nanorod array structures. Using an inverse design algorithm, we identify one optimized structure which achieves maximum theoretical light extraction while maintaining a high spontaneous emission rate. Overall, the optimized structure achieves a 48% increase in extracted power and a 20-48% increase in external quantum efficiency relative to the previous periodic design.