High refractive index IR lenses based on chalcogenide glasses molded by spark plasma sintering

V. Reux (1) , Laurent Calvez (1) , S. Billon (1) , A. Gautier (1) , H.-L. Ma (1) , Patrick Houizot (2) , F. Charpentier (3) , H. Tariel (3) , Z. Yang (4) , A. Yang (4) , Xianghua Zhang (1)

1 ISCR - Institut des Sciences Chimiques de Rennes
2 IPR - Institut de Physique de Rennes
3 DIAFIR
4 JSNU - Jiangsu Normal University

In this work, spark plasma sintering is used to mold non conventional chalcogenide glasses of high refractive index at low temperature (andlt;400°C). This equipment, usually used for sintering refractory materials, is presented as efficient for both densification and high precision molding of IR transparent bulks and lenses of telluride glasses. Thermo-mechanical and optical characteristics of the selected Ge25Se10Te65 glass composition were investigated showing a refractive index of 3,12@10 µm and with however a limited resistance to crystallization. Mechanical milling of raw Ge, Se, Te elements leads to a major amorphous phase with the formation of a small proportion of GeTe crystals. Remaining GeTe crystals induce a fast crystallization rate during the sintering process leading to the opacity of the material. SPS flash moldings were then performed using melt quenched glass powders to produce complex lenses. It has been found that the critical parameter to reach optimal IR transparency is mainly the powder granulometry, which should be superior to 100 µm to prevent from MIE scatterings. The possibility of producing high refractive index infrared lenses has been demonstrated even with unstable glasses against crystallization. © 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Mots clés: Chalcogenides; Crystals; Germanium compounds; Glass; Mechanical alloying; Milling (machining); Molding; Selenium compounds; Spark plasma sintering; Tellurium compounds; Temperature; Chalcogenide glass; Crystallization rates; Glass compositions; High refractive index; Mechanical milling; Melt-quenched glass; Optical characteristics; Powder granulometry; Refractive index

Domaines: Physique [physics]

V. Reux, Laurent Calvez, S. Billon, A. Gautier, H.-L. Ma, et al.. High refractive index IR lenses based on chalcogenide glasses molded by spark plasma sintering. Optical Materials Express, 2021, 11 (6), pp.1622-1630. ⟨10.1364/OME.427686⟩. ⟨hal-03249506⟩