In-volume 3D-Waveguides

Waveguides with variable cladding geometry Copyright: Fraunhofer ILT Waveguides with variable cladding geometry

3D-waveguides for beam guiding and -forming are written in the volume of glass by means of fs-pulsed laser radiation.

By focussing fs-pulsed laser radiation in the interior of transparent materials, the energy of the laser radiation is absorbed in the focal volume exclusively by non-linear processes. Thus, a volume which is limited to some m3 is intensely heated for a short time, and the material is melted in-situ. After resolidification, a small area with an enhanced refractive index may emerge.

Interference microscopy: Refractive index distribution in the cross-section of a waveguide in glass Copyright: Fraunhofer ILT Interference microscopy: Refractive index distribution in the cross-section of a waveguide in glass

Scanning the focus of the fs-laser radiation through the transparent volume allows to create three-dimensional structures with an enhanced refractive index, which serve as a waveguide. These 3D-volume waveguides are applicable in the field of integrated optics, for example in waveguide lasers, as connection between opto-electronic parts (optic printed circuit boards), or beam-forming devices.