Third-order nonlinear optical properties of GeSe2–Ga2Se3–PbI2 glasses

The third-order nonlinear optical (NLO) properties of new selenium-based GeSe2–Ga2Se3–PbI2 glasses have been measured using the optical Kerr effect (OKE) technique, with picosecond and femtosecond laser pulses. The 0.70GeSe2–0.15Ga2Se3–0.15PbI2 glass has the largest third-order optical nonlinear susceptibility in GeSe2–Ga2Se3–PbI2 glass system with χ(3) of 5.28×1012 esu. In addition, the response time of glasses is sub-picosecond, which is predominantly associated with electron cloud. Local structure of the glasses has been identified by using Raman studies, while the origins of the observed nonlinear optical response are discussed. The [Ge(Ga)Se4] tetrahedral and lone-pair electrons from highly polarizable Pb atom in glasses play an important role in enhanced NLO response. These results as well as their good chemical stability indicate that GeSe2–Ga2Se3–PbI2 glasses are promising materials for photonic applications of third-order nonlinear optical signal processing.