Fabrication of Dammann Gratings Inside Glasses by a Femtosecond Laser

Dammann grating is useful in information technology as an optical splitter. It is usually fabricated through complicated processes. Here we report on the direct fabrication of a 6 x 6 Dammann grating in a silica glass by an 800 nm femtosecond laser. We also discuss the relationship between diffraction efficiency of 1 x 2 Dammann grating and laser irradiation conditions.