We report on micro-structuring of iron-doped lithium niobate using femtosecond direct laser writing (DLW) technique. Formation of extended, stable index modulation micro-structures, such as diffraction gratings and linear waveguides is achieved by translation of a focused femtosecond laser beam inside lithium niobate crystals. From diffraction efficiency of the recorded gratings refractive index modulation amplitude of n ~ 10-3 is estimated. It is demonstrated that the recorded structures can be optically erased and re-written.
Direct laser writing of three-dimensional narrow bandgap and high refractive-index PbSe structures in a solution