Abstract

Focused femtosecond lasers are now being extensively applied in modifying refractive index in glasses and other materials for opportunities in creating 3-D optical circuits [1] and volume gratings [2]. Fast writing speeds (>60 mm/s), made available with high repetition rate femtosecond lasers (0.1 to 1 MHz), promise further extension to the fabrication of phase-contrast diffractive optical elements (DOEs), defined by finely written 3-D refractive index structures. Such buried 3-D phase structures are inherently protected from surface damage and promise wide latitude in optical design due to the distributed 3-D diffraction that is not possible with traditional surface relief DOEs.

© 2007 IEEE