Femtosecond laser fabrication of hybrid optical element in glass: volume grating embedded inside refractive lens

Femtosecond laser direct writing in glass is used to fabricate micro-optical elements with hybrid optical functions. Formation of hybrid refractive-diffractive elements by femtosecond laser direct writing in glass was demonstrated. By fabricating a diffraction grating inside a refractive lens, an element with two functions of light focusing and diffraction was fabricated. Hybrid optical element of volume grating embedded inside refractive lens element with a diffraction efficiency of 89% (at 633 nm wavelength) is achieved.