ABSTRACT
Ceramics, in particular glasses, have excellent optical properties which can be utilized for practical applications (1). One of the superior properties of glass as an optical material is high transparency, which makes it possible to use glasses as windows, lenses, prisms, waveguides and fibers for optical communications. In glass fibers for optical communications, Rayleigh scattering, absorption in infrared region and absorption tail in ultraviolet region determine the minimum value of optical attenuation, and the theoretical limit of optical attenuation was attained experimentally in a silica-based glass fiber (2,3). Another superiority is that glass can dissolve many transition metal and rare earth ions which give several functions to the glass. This property is utilized for developments of filters, photochromic glasses, fluorescent materials involving upconversion fluorescence, solid state lasers, Faraday rotators, fiber amplifiers and memory devices using spectral hole burning. Some examples of these materials will be presented in following sections.
