Active Waveguides

Planar active waveguides are made of glass doped primarily with erbium. These waveguides possess strongly non-linear optical properties, which allow a pump laser to amplify weak signals passing through the waveguide.
In 1998, glass compositions were further developed, which resulted in the first measurement of net amplification through a six cm long waveguide. A gain factor of 0.35 dB/cm was measured, which is more than sufficient to compensate for typical waveguide insertion losses.
By UV-inducing Bragg-gratings in these amplifying planar waveguides a number of lasers have been produced, which showed state-of-the-art performance. We regard these results as major breakthroughs for the group and for the technology employed.
Moreover, in 1998 the first steps were taken towards a hybridisation of diode pump lasers with planar silica waveguides. This together with the already successful integration of doped with non-doped glass will greatly add to the flexibility of the technology.
In parallel with these achievements, glass compositions and properties are researched on a more fundamental level. Particularly interesting is our discovery of self-organisation of erbium-precipitates at high temperatures. Moreover, a theoretical modelling, primarily based on density-functional-theory, of the chemical structure of Er/Al-doped silica has been initiated in 1998.