Sensitive measurement of optical nonlinearity in amorphous chalcogenide materials in nanosecond regime

The present work focuses on the nonlinear optical behavior of chalcogenide As2S3 film as well as on bulk material. The thin film of As2S3 grown by thermal evaporation and bulk glass developed by melt-quenched technique has been characterized using nanosecond pulses of Nd:YAG (532 nm) and Nd:YVO4 (1064 nm) laser. Using Z-scan technique, the laser induced nonlinear optical parameters viz. nonlinear refractive index (n2), nonlinear absorption coefficient (β) and third order nonlinear susceptibility (χ3) have been estimated. At 1064 nm excitation, the materials exhibit stronger nonlinearity as compared to that of 532 nm laser. In case of As2S3 thin film, observed nonlinearity attributes to two-photon absorption. The optical limiting response of chalcogenide film as well as bulk sample has also been reported. The study predicts that the As2S3 thin film is a better optical limiting material than bulk glass due to relatively higher nonlinearity and lower limiting threshold.

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► Synthesis of sample by melt quenched technique in case of bulk sample and by thermal evaporation in case of film.
► Z-scan technique, which is the one simple technique employed to exploit the optical nonlinear parameters.
► Comparison of results in bulk and thin film.