Three-dimensional Surfaces of Inorganic Materials Fabricated by Femtosecond Laser Lithography

Three-dimensional (3D) surfaces of inorganic optical materials were created by a combined process of nonlinear lithography and plasma etching. 3D patterns were directly written inside a KMPR-1050, which is chemically amplified negative-tone resists, on convex lenses by femtosecond laser-induced nonlinear optical absorption. Then, the patterns were transferred to the underlying substrates by CHF3 plasma. The fabrication of silica-based diffractive-refractive hybrid microlenses was demonstrated. We obtained micro-Fresnel lenses with smooth surfaces even on curved substrates. When 632.8-nm-wavelength laser light was. coupled to the hybrid lens, the primary focal length was 614 mu m. This result well agreed with theoretical value 617 mu m. Our combined process was useful for the precise fabrication of 3D surfaces based on inorganic materials.