Efficient high-harmonic generation in van der Waals ferroelectric NbOI${}_2$ crystals

Tianchen Hu, Feng Li, Junhan Huang +8

Layered NbOX${}_2$ ($X=\mathrm{Cl},\mathrm{Br},\mathrm{I}$), a member of the van der Waals ferroelectric family, exhibits intrinsic ferroelectricity and pronounced nonlinear optical responses, mak…