Chalcogenide glass thin films through inverted deposition and high velocity spinning - Electronics Letters

Introduction: The increasing sophistication of the industries requiring optical thin films from unconventional materials calls for alternative fabrication methods. Thin film for use in broadband and narrowband filtering applications, including dense wavelength division multiplexing (DWDM), optical amplification, switching, modulation of light signals, grating based devices, infrared light transmission, focusing, and as antireflection coatings are just some of the target areas, although other technological sectors including displays, aerospace, biomedical and defence have requirements. For the infrared (IR) transmitting family of glasses, in particular chalcogenides, several techniques for the production of thin films have been reported [1, 2]. Chalcogenide glasses (ChGs) contain elements from group VI of the periodic table as glass-forming anions and are generally opaque in the visible, with the exception of some sulphide glasses. The transmission window for ChGs extends from 1 mm to longer infrared wavelengths compared with oxide and fluoride glasses. The high-refractive index, enhanced mid-IR transmission in ChGs with reduced maximum phonon energy and ability to exhibit localised reversible or irreversible material changes when irradiated with light suggest these glasses are indeed interesting candidates for thin film development [3]. In this Letter we report the first steps in realising amorphous thin films in a ChG (gallium lanthanum sulphide, Ga:La:S) utilising the inverted deposition of the molten phase combined with high velocity spinning.