Direct fabrication of surface relief gratings in chalcogenide glasses by excimer laser interference lithography
in: Journal of Materials Science (2009)
In this paper we study the possibility to realise surface relief gratings in thin chalcogenide glass films by holographic exposure using a pulsed KrF excimer laser. Gratings with a period of 540 nm and depths of 100–300 nm were patterned at the surface of 1 lm thick films. Due to coupling of an incident near-infrared laser beam to waveguide modes a resonance-like polarisation dependent decline of transmission was observed at specific incidence angles. Just one laser pulse with a fluence of 12 mJ/cm2 per beam was sufficient to achieve the required grating parameters in sulphide glasses with low Tg. and/or chemical changes in oxide glasses. Thus a laser beam of moderate power can corrugate these glasses and surface relief micro-optical elements can be fabricated without any subsequent wet or dry processing [1–4]. In this paper we study the possibility to fabricate surface relief gratings in chalcogenide glass thin layers by holographic exposure using a pulsed KrF excimer laser. The gratings are characterised regarding their topology and the influence of the ultraviolet laser exposure on the chemical composition of the chalcogenide glass. The possibility to exploit them as resonant waveguide gratings at 1550 nm is also demonstrated.