Novel high sensitivity thermal managed eclipse Z-scan technique

Abstract

The field of Nonlinear Optics has provided many techniques to characterize photonic materials. The Z-scan method is a well estabileshed technique that exploits front wave distortions of the light beam to determine the nonlinear properties of optical materials. Several variations of the methods have been developed, as the eclipse Z-scan that can provide up to two orders of magnitude higher sensitivity than the original Z-scan set-up. We report a new variation of the Z-scan method to characterize the third-order optical nonlinearity of photonic materials. By exploiting the combination of the eclipse Z-scan with thermal nonlinearity management, we demonstrate an improvement in sensitivity and flexibility of the method to simultaneously characterize the thermal and nonthermal nonlinearity of optical materials. The method is demonstrated by measuring the nonlinear refractive index in CS₂, SiO₂ and H₂O as standard materials, and also of a biomaterial, the amino acid Tryptophan in water solution, using the same experimental set up based on a femtosecond Ti-saphire laser operating at 76MHz repetition rate.