Schott Glaswerke

Wolfgang Siefert

Ralf T Kersten

Volker Paquet

Hartmut Bauch

Peter Krause

Ulrike Jost

A method for the manufacture of a light wave guide providing a cladding and a light conducting core, from a glass tube, showing a material on or below its inner surface which forms the core of the finished light wave guide comprising at least one substance which is diffused out selectively of this material, forming the core subsequently, into the interior space of the glass tube, whereby during the diffusing-out process the partial pressure of the diffusing-out substance in the interior space of the glass tube is maintained as small as possible, whereby a premature collapsing of the glass tube during the diffusion process is prevented by adjusting an overpressure in the glass tube, that the glass tube after the diffusing out process is largely collapsed by rinsing with a rinsing gas and in a last collapsing step is completely collapsed to a rod (perform) without rinsing with a rinsing gas and that the rod is subsequently drawn out to a fiber.

Method for the manufacture of a light wave guide

Planar single-mode optical waveguides which can conduct light with defined polarisation have so far been embedded in, for example, a cladding made from crystalline LiNbO.sub.3. The crystalline structure of the cladding produces disadvantageous properties such as the fact that the birefringence depends on the geometric profile of the guide, relatively high optical loss, poor fibre coupling, birefringence rigidly fixed by material constants, and a costly manufacturing process. The new process results in an optical waveguide in which both the cladding and the actual guide itself are made of glass with a certain composition, thereby avoiding the disadvantages stated. With the help of a non-isothermal plasma CVD process a light-guiding core region (1) is surrounded on a substrate (4) by cladding layers (2, 2') and a cladding region (3, 3'), the thermal coefficient of longitudinal expansion of the cladding region (3, 3') differing markedly from that of the two homogeneous cladding layers (2, 2'). The core region has either a higher or approximately the same refractive index as the cladding region. Use of the optical waveguide is as a polarisation-receiving or polarising single-mode optical waveguide.

Process for producing a planar optical waveguide

A planar lightwave guide with light-conducting core zones in light conducting strips is made by the precipitation out of a gaseous phase onto a substrate a thin, glass-like strata in accordance with a programmed schedule so as to allow a predetermined refractive index curve to be obtained to thereby form a light-conducting core zone and protective sheathing layers adjacent to the core zone. The improvement in the method is characterized in that the precipitation out of the gaseous phase is obtained by application of a heterogeneous reaction and in that after the formation of the light-conducting strips, the refractive index of the core-forming strata is modified in a targeted manner in a lateral marginal region of the strips by diffusing out the doping substance which determines the refractive index curve in the core zones. Subsequently these strips and the substrate are coated with a covering layer of a material having a lower refractive index than that of the core zone material.

Method for making planar lightwave guides

A method of making a planar lightwave-guide with light-conducting core zones by precipitation out of a gaseous phase a thin, glass-like strata onto a substrate in accordance with a controlled schedule so as to allow a predetermined refractive index curve to be obtained to thereby form a light-conducting core zone and sheathing layer adjacent to the core zone. The improvement is characterized in that the precipitation out of the gaseous phase is obtained by application of a heterogeneous reaction and in that initially a first layer with a doping medium which decreases the refractive index is applied to the substrate and thereafter a masking layer is applied on top of the first layer to act as a diffusion barrier with respect to the doping medium. The masking layer is structured by conventional masking technology in accordance with a desired strip or band pattern. Thereafter, the substrate provided with these layers is heated to a degree sufficient to diffuse the doping medium out of the unmasked regions of the first layer and thus forming at least a portion of the core zone of the light-conducting regions. Further layers are then applied in which the refractive indices are controlled to complete the lightwave-guide.

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Mainz, Germany

Wolfgang Siefert