Form birefringence induced in multicomponent glass by femtosecond laser direct writing.
We demonstrate a new kind of form birefringence in lithium niobium silicate glass induced by femtosecond laser direct writing. By combining electron backscatter diffraction and transmission electron microscopy, we reveal a self assembled nanostructure consisting of periodic phase change: nonlinear optical nanocrystals embedded in a network of "walls" in a vitreous phase. These "walls" are aligned perpendicular to the laser polarization direction. This self organized nanostructure may successfully explain the origin of the laser induced birefringence in this multicomponent glass quite differently from pure silica. These findings highlight a spectacular modification of glass, and enable construction of a high contrast three dimensional refractive index and birefringent structures at the micrometer scale in multicomponent glasses.
Optics letters