F 2 -laser applications for machining optoelectronic microstructures

Abstract

We report studies of material processing using the VUV F 2 laser which, by virtue of its low threshold, high resolution 'machining' capability, may bring advantage to laser-based optoelectronic and photonic device fabrication. For example, probe beam deflection and etch rate studies of polymethylmethacrylate (PMMA) show this has a low ablation threshold, F T =20mJcm -2 , and a large effective absorption coefficient, 1.6 ×10 5 cm -1 , at 157nm, permitting high-resolution etching at modest fluence. The smooth ablated surfaces and low degree of thermal damage obtained with this laser make it well suited to machining structures such as relief gratings in PMMA. We also describe new results on producing fibre Bragg gratings with the 157nm laser. It is shown that these gratings can be written in a non-sensitised single mode fibre (Corning HI 980) with a low fluence and low total dose.