Mode-index waveguide lens with novel gradient boundaries developed for application to optical recording

A new type of mode-index waveguide lens is presented that has acircular gradient-index boundaries. These lenses have relatively large apertures and are fabricated by physical vapor deposition by using organic materials. A deposition mask that is accurately defined by using lithographic processing techniques was used to shape the lens boundaries during the addition of the lens to the waveguide. A comprehensive analysis of the lens system is presented. After adjusting the model to have aberrations that are comparable with those of the fabricated lens, spot size and sidelobe intensity values were nearly identical for the theoretical and experimental systems. The application of these lenses to optical recording technology is demonstrated by the generation of focus and tracking error signals.