Rare-earth spontaneous emission modification in direct laser written lithium niobate three-dimensional photonic crystals

This manuscript describes the fabrication and optical characterization of direct laser written erbium-ytterbium codoped lithium niobate three-dimensional photonic crystals. Fourth and sixth order Bragg stop gaps are demonstrated for face centred tetragonal and face centred cubic lattices, respectively, and the spontaneous emission from rare-earth ions (for the 1.5 μm wavelength emission channel from erbium ions) is demonstrated for the first time in a three-dimensional lithium niobate photonic crystal.crystal