High-Q asymmetric polymer microcavities directly fabricated by two-photon polymerization

We experimentally report high-Q asymmetric polymer microcavities with highly directional coupling, which are directly written by two-photon polymerization of zirconium/silicon hybrid sol-gel. Benefiting from the high spatial resolution and three-dimensional nature of this direct laser writing technique, the polymer microcavities not only have the designed boundary shapes that are required for highly directional emission but also possess high-Q factors exceeding 10⁵ that approach the polymer absorption limit. The free-space coupling fractional dip, dependent on the incident far-field direction, is used here to characterize the emission properties by the mutual correlation between the coupling and the directional emission. These high-performance polymer microcavities hold great potential in the fields of low-threshold microlasing and high-sensitivity optical biosensing.