Chalcogenide Photonic Crystal Fibers for Near and Middle Infrared Applications

Abstract

Chalcogenide glasses are based on sulphur, selenium, tellurium and the addition of other elements such as arsenic, germanium, antimony, gallium, etc. Chalcogenide fibers present numerous applications in the IR field, such as telecommunication at 1.55 mum, spectroscopy and military systems in the two atmospherics windows (3-5 mum and 8-12 mum). One of the interests of chalcogenide glasses is to associate high non linear properties with their Infrared transmission from 0.51 mum to 12-18 mum depending on the composition. Indeed, chalcogenide glasses present high third order optical properties, 100 - 1000 times as high as the non linearity of silica glass at 1.55 mum. For many applications, single mode fibers must be obtained. The first way studied is the preparation of classical step index fiber with a core clad structure. This way considers two glass compositions (core clad) with compatible thermal and optical properties. The second way more original, is the realisation of microstructured fibers. Holey fibers have a broad range of optical properties thanks to their structures. In this context, we have developed microstructured fibers for mid IR transmission with different geometries and properties: multimode, endlessy single-mode, small and large mode area. We work also on the improvement of the transmission properties by chemical and physical purifications of the glasses. For the 3-5 mum window, we have studied the 2S1G glass composed with sulphur, antimony and germanium. For the 8-2 mum window, we study the TAS glass composed with tellurium, arsenic and selenium. For the first time to our knowledge, a microstructured fiber in 2S1G glass has been characterised at 1.55 mum and 3.39 mum and a microstructured fiber in TAS glass has been obtained.