Optical components made by blasting craters into glass

The trend for making electronics and computing components smaller reaches a roadblock when it comes to some telecommunications devices. The need to carry signal means that optical fibres must be used, and these need to be long to work effectively. To avoid this problem, engineers are now using planar waveguides, which conduct light waves across a two-dimensional surface rather. Researchers at Leeds University have now developed a new way to make planar waveguides by bombarding a specific type of glass with powerful laser pulses.

The glass in question is made from compounds of zinc, sodium and tellurium, and is doped with erbium, a rare earth metal. Erbium is useful in these technologies because one of its electrons shifts orbital when it absorbs a photon of 1.5µm wavelength, a standard light wavelength used in telecommunications technologies. To make the waveguide, the researchers had to coat the glass with a thin layer of erbium, and to achieve this they fired a high-intensity laser at the surface of the doped glass. This blasted a minute crater into the material, producing a plume of ejected material that fell back to the glass surface and coated it with the metal. Using an ultrafast pulsed laser, they repeated the process many times to make a large area coating.