Fabrication of buried channel waveguides in fused silica using focused MeV proton beam irradiation

Low-loss channel waveguides have been fabricated in fused silica using a beam of MeV protons focused down to a spot size of several microns. By using a combination of beam and sample scanning, single- and multimode graded index waveguides with lateral dimensions down to approximately 5 /spl mu/m/spl times/5 /spl mu/m have been fabricated using ion doses in the range (3/spl times/10/sup 14/)-(6/spl times/10/sup 16/) ions/cm/sup 2/. Typical beam currents in the range 100 pA-10 nA were used. Optical mode profiles have been measured at 670 nm and propagation losses of the order of 3 dB/cm measured in unannealed samples. Annealing the substrate for 1 h at 500/spl deg/C reduced these losses to below 0.5 dB/cm.