Linear and nonlinear optical properties of co-sputtered Ge-Sb-Se amorphous thin films

• Published in: Optics letters Vol. 45; no. 6; p. 1523
• Main Authors: Halenkovič, Tomáš, Gutwirth, Jan, Kuriakose, Tintu, Bouška, Marek, Chauvet, Mathieu, Renversez, Gilles, Němec, Petr, Nazabal, Virginie
• Format: Journal Article
• Language: English
• Published: United States 15.03.2020
• ISSN: 1539-4794
• DOI: 10.1364/OL.386775

Amorphous Ge-Sb-Se thin films were co-sputtered from ${{\rm GeSe}_4}$GeSe and ${{\rm Sb}_2}{{\rm Se}_3}$Sb Se targets. Depending on the film composition, linear optical properties were studied by ellipsometry. The Kerr coefficient and two-photon absorption coefficient were estimated using Sheik-Bahae's formalism for co-sputtered films of ${{\rm GeSe}_4} {\text -} {\rm Sb}_2{{\rm Se}_3}$GeSe -Sb Se compared to ${{\rm GeSe}_2}{\text -}{\rm Sb}_2{{\rm Se}_3}$GeSe -Sb Se pseudo-binary system and ${{\rm As}_2}{{\rm Se}_3}$As Se as reference. The Kerr coefficient was found within the range of $4.9 {\unicode {x2013}}- 21 \times {10^{ - 18}}$4.9--21×10 . Quantitatively by means of a figure of merit at 1.55 µm, thin films with compositions of ${{\rm Ge}_7}{\rm Sb}_{25}{\rm Se}_{68}$Ge Sb Se and ${{\rm Ge}_9}{\rm Sb}_{20}{\rm Se}_{71}$Ge Sb Se having an estimated Kerr coefficient of about ${10.1} \times {10^{ - 18}}\;{{\rm m}^2}{{\rm W}^{ - 1}}$10.1×10 m W and ${13.4} \times {10^{ - 18}}\;{{\rm m}^2}{{\rm W}^{ - 1}}$13.4×10 m W should be considered for the future nonlinear optical integrated platforms. Such compositions being close to ${({{\rm GeSe}_4})_{50}}{({{\rm Sb}_2}{{\rm Se}_3})_{50}}$(GeSe ) (Sb Se ) pseudo-binary (i.e., ${\rm Ge}_{7.5}{\rm Sb}_{25.0}{\rm Se}_{67.5}$Ge Sb Se ) provides just the trade-off between a high Kerr coefficient and low optical losses related to two-photon absorption.