Determine the origin of static wavefront distortions

Determine the physical origin of the static background refractive-index perturbations that distort the wavefront in the two-dimensionally programmable lithium-niobate slab waveguide and cannot be explained by damaged facets or misalignments alone.

Background

The digital model for the programmable lithium-niobate slab waveguide includes a static background refractive-index perturbation, denoted by Δnbg(x,z)\Delta n_{\mathrm{bg}}(x,z), to reproduce experimentally observed wavefront distortions. The paper states that these distortions are not adequately accounted for by damaged facets or alignment errors, leaving their physical source unresolved.

References

The origin of said distortions is unclear, and the distortion cannot be modeled by damaged facets or misalignments alone.

— Lithography-free in situ photonic inverse design  (2610.10404 - Zhao et al., 7 Oct 2026) in Section 2.2, “Digital model”