MATERIAL DISPERSION IN QUARTZ GLASS FIBER WAVEGUIDES.

The dispersion of the refractive index n ( lambda ) of the core (GeO//2 plus SiO//2) and cladding (SiO//2) of a two-layer fiber blank was determined in the wavelength range 0. 8-2. 6 mu ; similar determinations were made for KV, KSG, and KV70 (anhydrous) quartz glasses. The spectral distribution of the material dispersion lambda /c)(d**2n/d lambda **2) and numerical aperture of the waveguide layer were determined. Zero material dispersion of various samples of pure SiO//2 was observed in the range 1. 2-1. 30 mu and similar results were obtained for the fibers at 1. 3 to 1. 32 mu . The near-field method was used to determine the spectral distribution of the aperture of a glass fiber waveguide drawn from the prepared blank and it was found that the material dispersion in the finished waveguide was the same as in the blank (within the limits of the experimental error). In the 1. 6 mu range, where the total losses in the waveguide were less than 1 dB/km, the material dispersion amounted to 24 psec. (nm multiplied by (times) km)** minus **1.