Infrared transmitting glasses and glass-ceramics

The demand for infrared materials which exhibit higher performance is still growing; both on the thermal and mechanical side as well as on the width of the optical window, with an extension of the transparency towards the long wavelength region to satisfy the requirements of space applications. Glasses as well as glass-based ceramics offer the advantage of unique rheological properties allowing molding and fiber drawing. In controlling the nucleation/growth process in a chalcogenide glass modified by an alkali halide, it has been possible to develop a new generation of glass ceramics containing nanosize grains and transparent in the mid infrared. For the optical exploration of the universe, new low phonon glasses transparent in the 20 μm region and beyond are needed and to reach this goal a new family of telluride glasses was developed in combining Te with Ge with the addition of Gallium or Iodine for stabilization. These new optical glasses are transparent from 2 to 20 μm and can be drawn into fiber.