Inverse designed photonic crystal cavity enhanced emission from perovskite colloidal quantum dots

Solid-state cavity quantum electrodynamic systems are a fundamental building block in the development of emitter-photon interfaces. In this context, photonic crystal cavities are especially interesting because of their ability to induce strong light-matter interactions. L3 photonic crystal cavity is an attractive candidate because it is easy to fabricate and the fundamental mode has a large quality factor and low mode volume. However, the bottleneck in the performance of L3 cavities lies in the diverging far-field emission of the fundamental mode, which results in poor collection efficiency. Traditional cavity optimization paradigms improve the far-field emission at the cost of the quality factor. Alternate cavity designs, such as nanobeam cavities, overcome this limitation but are exceedingly challenging to fabricate.

In this work, we employ inverse design to simultaneously optimize the quality factor and tailor the far-field to be gaussian-like thereby boosting the collection efficiency of the L3 cavity to near unity. Coupling these inverse-designed cavities to ensembles of perovskite colloidal quantum dots, we experimentally demonstrate a 20x improvement in coupling efficiency and a 3x increase in quality factor. Additionally, through numerical analysis, we investigate the robustness of the inverse-designed cavities against fabrication imperfections. This work represents a step toward scalable photonic quantum information processing platforms with efficient cavity-emitter interfaces.