We report on the accurate measurement of nonlinear ellipse rotation (NER) by means of a phase-sensitive method employing a dual-phase lock-in. The magnitudes and signs of pure refractive electronic nonlinearities of silica and BK7 were determined with this new method using 150 femtosecond (fs) laser pulses at 775 nm. Experimental and theoretical analyses of the NER signal were carried out and the results were compared to those obtained with the Z-scan technique.

We investigated the magnitude and origin of the nonlinear refraction in several solvents with the nonlinear ellipse rotation measurements as a function of the pulse duration in the range from 60fs to 2ps. Due to the presence of non-instantaneous nuclear contributions concurrently with the nearly instantaneous electronic nonlinearity, solvents present effective refractive nonlinearities that depend on the pulse duration. By proposing an empirical model where the nonlinearity grows exponentially with the pulse duration normalized to the response time, we could separate contributions from fast isotropic and slow nuclear reorientational nonlinearities. Z-scan measurements were also carried out to support our model.

No abstract

This work reports on the spectral dependence of both nonlinear refraction and absorption in lead-germanium oxide glasses (PbO-GeO₂) containing silver nanoparticles. We have found that this material is suitable for all-optical switching at telecom wavelengths but at the visible range it behaves either as a saturable absorber or as an optical limiter.

Chalcogenide glasses (ChGs) are promising materials for nonlinear optical applications due to their elevated third-order optical susceptibility. Nonetheless, oxidation and photorefractive effects make the characterization and processing of this class of materials an intricate process. Employing ultrashort laser pulses, we were able to investigate the optical nonlinearities of As 2 S 3 thin films doped with Ag 2 S nanocrystals, as well as produce channel waveguides. The results showed that the nonlinear refractive indexes of these films are in the order of 2.3-5.2 x 10 −18 m 2 /W at wavelengths in the range of 775-1600 nm. Such film revealed to be proper for the development of nonlinear optical devices, since we have demonstrated the functionality of an 8.7 mm long waveguide for spectral broadening femtosecond IR pulses.

No abstract

a b s t r a c tThis paper reports on the fabrication and characterization of waveguides inside of a dye doped-organic/inorganic bulk material using femtosecond laser microfabrication. Rhodamine B-doped GPTS/TEOS-derived organic/silica monolithic xerogels with excellent optical quality were prepared by sol-gel method. The influence of the dye concentration on the samples optical properties was also investigated in order to choose the proper one to be used for producing the waveguides. After investigation of parameters to fabrication in xerogels, such as, scan speed effects and pulse energy, we produced waveguides in bulks doped with 0.5 mmol/L of Rhodamine B. Propagation losses in the single mode waveguides, at 632.8 nm wavelength, were obtained.

No abstract