Open microcavities

Project overview

An alternative way to epitaxial growth of a full microcavity is to mechanically assemble it using separate mirrors and quantum wells (QWs). This can be achieved, for example, by attaching a top DBR and bottom DBR, with grown on top of it QWs, to two separate nano-positioner stacks, and then bring them together to form a microcavity with a small separation between the two mirrors. Ensuring high stability of the system and quality of the mirrors it is possible to achieve strong coupling regime.

In our experiments we use a tunable cavity, which consists of a dielectric DBR containing concave features of various radii of curvature (RoC) and a semiconductor DBR with a cavity region containing QWs grown above. The hemispherical cavity geometry leads to strong lateral photonic confinement which is then imprinted in the polariton wavefunction. The combination of both longitudinal and lateral confinement creates photonic confinement in 3-dimensions and leads to the formation of zero-dimensional polaritons. This confinement increases the polariton-polariton interaction and may lead to the observation of the polariton blockade effect in single or coupled polariton boxes.

The open nature of the system allows mechanical exfoliation of 2D atomic layered materials with van der Waals-like interlayer coupling on the bottom DBR. The tunability of the resonant frequency of the microresonator then allows the cavity to be tuned into resonance with the exciton emission.