Toward Highly Reliable, Precise, and Reproducible Fabrication of Photonic Crystal Slabs on Lithium Niobate

Nanostructuring lithium niobate (LN) is recently a hot topic since it can achieve miniaturized footprints in comparison with bulk LN. Due to the challenging machining on this material, the different available techniques still present uncontrolled constraints that forces the LN-based photonic structures behavior to be far from the theory. In this paper, we design a photonic crystal structure based on free standing thin films of LN where the vulnerabilities of design with respect to the fabrication constraints are deeply studied in order to minimize and compensate its impact to the device performances. The developed structures (based on Fano resonances) exhibit a precision in terms of resonance wavelength of $\pm {\text{18 nm}}$ and an aspect-ratio decrease of ${\text{54.99}}{\%}$ accompanied by an outstanding resonant line shape agreement with the theory that is a novel result in nanostructured LN. Furthermore, the implemented resonance takes advantage of the exceptional light confinement provided by the Fano phenomenon enhanced by a band folding effect, exhibiting an outstanding average slope of 0.64 dB/nm. These results demonstrate a step forward in the fabrication of high reproducible, miniaturized, and power efficient devices whose technology can advance the frontiers of the current electrooptical devices.