Fabrication of 3D microoptical lenses in photosensitive glass using femtosecond laser micromachining

We describe the fabrication of microoptical cylindrical and hemispherical lenses vertically embedded in a photosensitive Foturan glass by femtosecond (fs) laser three-dimensional (3D) micromachining. The process is mainly composed of four steps: (1) fs laser scanning in the photosensitive glass to form curved surfaces (spherical and/or cylindrical); (2) postannealing of the sample for modification of the exposed areas; (3) chemical etching of the sample for selective removal of the modified areas; and (4) a second postannealing for smoothening the surfaces of the tiny lenses. We examine the focusing ability of the microoptical lenses using a He-Ne laser beam, showing the great potential of using these microoptical lenses in lab-on-a-chip applications. PACS 42.62.-b; 81.05.Kf; 82.50.Pt