Visit us at Photonics West

At the Photonics West 2008 (presentation 6873-36) we introduced our rare earth doped fused bulk silica which overcame the typical geometrical limitations of other well known techniques such as the MCVD solution doping process. Our unique production technique is based on the sintering of Yb-doped granulates of high-purity SiO2 particles.

Using production techniques such as mechanical drilling, grinding, fire polishing, gas phase etching, plasma outside deposition of fluorine doped fused silica and overcladding, we have processed our Yb-doped silica rods into different laser active double cladding fiber preforms with very smooth and flawless interfaces between core and cladding. These preforms possess an un-doped pump cladding with a round or the so called 2D and 4D pump cladding shape and a fluorine doped outer cladding. The preforms have been successfully drawn into multimode fibers with an outer diameter of 1000 µm and an active core diameter typically about 100 µm.

The fiber cross section design, the quality of the interfaces between active core, un-doped pump cladding and F-doped outer cladding and the core material composition are all important factors for the laser performance of these fibers. We have investigated the refractive index profiles and the intrinsic stress profiles of different preforms to visualize these interface effects. Detailed studies of the laser performance of these fibers will be presented.