Three-Dimensional Mid-Infrared Photonics: Recent Progress in Ultrafast   Laser Writing of Waveguides
  We present here our recent progress in the three-dimensional (3D) direct laser writing (DLW) of step-index core waveguides inside diverse technologically relevant dielectric substrates, with specific emphasis on the demonstration of DLW mid-infrared waveguiding in the whole transparency range of these materials. 
Airan Rodenas, Robert R. Thomson, Guillermo Martin, Pierre Kern, Ajoy   K. Kar
physics.optics astro-ph.IM