Metal-organic frameworks as competitive non-linear optical materials: light conversion and structural modification

Abstract

The integration of metal-organic frameworks (MOFs) as coordination polymers into the field of nonlinear optics and light conversion has recently attracted significant attention. However, the challenge of achieving high endurance and efficiency for light conversion throughout the entire visible range using a single MOF crystal persists. In this work, we present the design of a non-centrosymmetric MOF based on a 1,3,5-benzenetricarboxylic acid ligand and Erbium (Er) ions, which demonstrates efficient and simultaneous generation of multiple second and third optical harmonics (SHG, THG) across a wavelength range of 400 to 750 nm. Through a combination of optical experiments we have confirmed the effectiveness of SHG and THG in the MOF single crystals. These phenomena are caused by the specific MOF space group and the associated dipole moment. The observation of coherent light conversion throughout the entire visible range by MOF single crystals under ambient conditions enables the realization of multicolor (up to 3) emission, which is essential for modern laser technologies.