Ultracompact generation of self-similar microbeams with self-healing property

Microscale optical beams can be especially useful when generated by micrometric platforms. Here, we achieve one such combination by exploiting the concept of the self-similar beam. Fresnel diffraction-based reformulation of the self-similar beam leads to a compact platform design realizable with 3D-printing of low-index photopolymers. The final design, refined through numerical simulations, is only 1050 nm high and 5500 nm wide and generates bright-core microbeams out of unstructured plane wave excitation. Experimentally, we realized the design by 3D-nanoprinting and produced self-similar bright beams that maintained ±15 µm beam width over the millimetric propagation range. Their characteristics are close to those of quasi-non-diffracting microbeams. We also confirmed the self-healing characteristic of the microbeams.