Characterisation of GaLaS chalcogenide glass thin-film optical waveguides, fabricated by pulsed laser deposition

Abstract

The fabrication of stoichiometric thin-film optical waveguides of GaLaS via a pulsed laser deposition technique is reported. Stoichiometric films are grown by ablating GaLaS bulk glass with a KrF excimer laser (λ = 248 nm) at an incident laser flux ⩾ 3.5 J/cm 2. The composition of the films is determined by energy-dispersive X-ray analysis and the refractive index is measured by a dark-mode prism coupling technique. Photoinduced structural rearrangement of the as-deposited films leads to a blueshift in the visible absorption edge and a permanent refractive index change, Δ n, of −1%. On the basis of these results, grating structures have been written with both blue light, and e-beam addressing, and their suitability for integrated optical structures assessed.