L. Sarger

Nonlinear optical properties of some tellurium (IV) oxide glasses

Abstract Thermal and optical properties of glasses of the TeO 2 | ZnO, TeO 2 | Nb 2 O 5 and TeO 2 | M 2 O | Nb 2 O 5 (M = Li, K) systems have been investigated. Linear and nonlinear indices of the materials increase with the TeO 2 rate. The highest values are obtained for the niobium tellurite glasses emphasizing the particularly significant role of NbO 6 octahedra in the optical response.

Time-resolved absolute interferometric measurement of third-order nonlinear-optical susceptibilities

A modified Mach–Zehnder interferometer has been built for measurement of nonlinear-optical susceptibilities in bulk materials. Both slow- and fast-intensity-dependent refractive-index changes can be measured in absolute value, with femtosecond time resolution, high sensitivity, and precision, by means of a new fringe-locking technique. Results on fast nonlinearities of CS2 liquid and glasses are presented.

SPICE modeling of the transient response of irradiated MOSFETs

A new SPICE model of irradiated MOSFET taking into account the real response of the four electrodes is proposed. A comparison between SPICE-generated transient response and PISCES device simulation demonstrates the accuracy benefits when used in complex electronic architectures.

Planar waveguides formed by Ag + –Na + ion exchange in nonlinear optical glasses: diffusion and optical properties

All-optical communication systems are the subject of intense research related to the integration of nonlinear optical materials. In sodiocalcic borophosphate glasses that contain niobium oxide and exhibit high nonlinear optical indices, planar waveguides have been formed by a Ag(+)-Na(+) ion-exchange technique. WKB analysis has been used to characterize the diffusion profiles of silver ions exchanged in glass substrate samples chemically by an electron microprobe technique and optically by an M-line technique. These methods permit the Ag(+) penetration depth and diffusion profile shape and index profiles to be determined. The results are analyzed and discussed in relation to Ca(2+) concentration and exchange conditions in glasses. The Ag(+) diffusion in these glasses can be almost entirely controlled for index-profile engineering.

High-Frequency Response in Ferroelectric BaSrTiO3 Thin Films Studied by Terahertz Time-Domain Spectroscopy

We have measured the dielectric properties of BaTiO3–SrTiO3 thin films, deposited on fused silica substrates, in the MHz and THz frequency regions. Different experimental Chemical Vapor Deposition parameters were analyzed to improve dielectric properties of these thin films. In particular, we clarify pressure and oxygen percentages during the deposition of the thin layer. The complex permittivity function of the film was accurately determined between 100 GHz and 1 THz. We show that the real part of the dielectric behavior at very high frequencies follows the same tendency of the low frequency dielectric behavior also measured. These results are correlated to X-ray diffraction and RBS patterns, which show that the cationic ratio (Ba+Sr)/Ti increases from about 0.6 to 0.9 as sputtering pressure changes from 1 to 5 Pa, leading to better dielectric properties.

Contribution of XAFS analysis to the study of the correlation between optical nonlinearity and the geometry of titanium sites in glasses

Abstract In the context of a general investigation of the nonlinear optical properties of glasses, we report here the effect of introducing TiO 2 in various silicate and borophosphate glass matrixes. A correlation study is carried out between the magnitude of the measured nonlinear indices n 2 of these materials and the local structure around titanium which can be deduced using XAFS analysis. This allows to point out that square-based pyramids are particularly efficient when present in borophosphate glasses.

High power, linearly polarized, continuously tunable ytterbium-doped rod-type photonic crystal fiber laser

An ytterbium-doped fiber laser continuously tunable from 976nm to1120nm and delivering up to 30W of average power linearly-polarized is demonstrated. Moreover the bandwidth of our system can be tuned from 100pm to more than 1nm.