We report a new variation of the conventional Z-scan method to characterize the third-order optical nonlinearity of photonic materials. By exploiting the combination of the eclipse Z-scan with a thermal nonlinearity management technique, 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 CS(2), SiO(2) and H(2)O, standard materials, and also in a biomaterial, the amino acid Tryptophan in water solution, using a femtosecond Ti-Sapphire laser operating at 76MHz repetition rate.

We report on the ultrafast nonlinearity of antimony polyphosphate glasses measured using the Kerr shutter technique. The nonlinear refractive index, n2, was (1.1±0.2)×10−14 cm2/W at 800 nm, and enhancement of n2 by ≈80% was observed by adding 10% of lead oxide in the glass composition. The full width at half-maximum of the third-order correlation signal was 150 fs, which implies a fast response of the samples (⩽100 fs). Nonlinear absorption was negligible in the range of intensities used.

Third-order nonlinearity one order of magnitude larger than silica is measured in bismuth-borate glasses presenting a fast response ͑Ͻ200 fs͒. The results for the sign and magnitude of the nonlinearity were obtained using a combination of the eclipse Z scan with thermal nonlinearity managed Z scan, whereas the Kerr shutter technique was employed to obtain the electronic time response of the nonlinearity, all performed with 76 MHz repetition rate 150 fs pulses at 800 nm. Conventional Z scans in the picosecond regime at 532 and 1064 nm were also independently performed, yielding the values of the third-order nonlinear susceptibilities at those wavelengths. The results obtained for the femtosecond response, enhanced third-order nonlinearity of this glass ͑with respect to silica͒, place this glass system as an important tool in the development of photonics devices. Electro-optical modulators, optical switches, and frequency converters are some of the applications using second-order nonlinear properties of the Bi-glass based on the rectification model.

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 CS 2 , SiO 2 and H 2 O 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.

No abstract