Fiber waveguide with a fluorine-doped cladding and a pure quartz glass core

The rod-in-tube method was used for the first time in the Soviet Union to construct fiber waveguides with a pure quartz glass core, formed by the axial deposition technique, and a fluorine-doped quartz cladding formed by the technique of plasmachemical deposition inside a quartz jacket tube. In the case of a fiber waveguide with a numerical aperture of 0.18 the optical losses ranged from 3 dB/km at the wavelength of 0.85 μ to 1.4 dB/km at 1.5 μ. The results of an investigation of the radiation-optical stability of these fiber waveguides indicated that they were not inferior (in respect of this characteristic) to the best foreign devices. The high radiation optical stability was due to the purity of the waveguide materials.