| Building large optical communications network requires new all fiber components that will permit to change rapidly the frequency of the signal in a device based on silica fibers. The discovery of self induced second harmonic generation in silica has created a great hope of developing very fast all fiber modulators, frequency converters and so on.; Among the techniques that have been discovered to create a large second order non-linearity (χ(2)) in fused silica, ultraviolet poling and thermal poling are the most studied and reproducible. The maximum χ (2) that can be induced in silica with these techniques is about 0,2 pm/V to 5 pm/V.; Two models have been developed for explaining the creation of the χ (2) in fused silica. The first which is largely adopted by scientists in this field is the space charge model. The second model elaborated is the orientation of dipolar moieties in the matrix of the amorphous silica. (Abstract shortened by UMI.)... |
