Three-dimensional micro-optical components embedded in photosensitive glass by a femtosecond laser

We show that three-dimensional micro-optical components can be embedded in a photosensitive glass by a femtosecond (fs) laser. After exposure to the tightly focused fs laser beam, latent images are written inside the sample. Modified regions are developed by a postbaking process and then preferentially etched away in a 10%-dilute solution of hydrofluoric acid. After this process, hollow internal structures are formed that act as a mirror and a beam splitter. Furthermore, we find that postannealing smoothes the surfaces of the fabricated hollow structures, resulting in great improvement of their optical properties.