Xiang-Hua Zhang is Research director of the CNRS (National centre for scientific research) and the director of the laboratory of glasses and ceramics in the Institute of chemical science at Rennes, France. He got his bachelor in Zhejiang University, China in 1983 and PhD degree in University of Rennes I, France in 1988. He worked in the laboratory of glasses and ceramics until 1996 when he left to found the Umicore IR glass company, for producing chalcogenide glass optics. He came back to the CNRS in 2002. He is mainly specialized in chalcogenide glasses and ceramics mainly for infrared photonic applications and more recently also for energy conversion. He is co-inventor of 22 patents and co-author of more than 470 peer-reviewed publications. 

Controlled crystallization in Chalcogenide glasses

Chalcogenide glasses are particularly interesting for middle and far infrared photonics. The crystallization behaviour is one of the key parameters for composition selection because of the fabrication process using sealed silica tube, which does not allow high cooling rate. Controlled crystallization is an efficient way to create glass ceramics with original properties such as improved mechanic properties, enhanced photo-luminescence and photo-conductivity as well as unusual optical properties. For photonic applications, the key issue is to obtain sufficient property enhancement while keeping the infrared transmission. It is also interesting to point out that some unusual crystalline phases, with unique properties, can only be obtained with controlled crystallized in selected chalcogenide glasses. Different challenges and applications will be discussed.