Second harmonic generation was obtained with an interesting efficiency in thermally poled sulfide glass. The best results obtained to date for chalcogenide glasses were on a Ge-Sb-S system thanks to an adapted treatment of thermal poling. The poling parameters like temperature (100-310 °C), applied voltage (2.5-4 kV)and duration (5-60min) were explored. A large NL second-order susceptibility χ(2) of about 10 ± 0.5 pm/V was measured. The nonlinear susceptibility profile as a function of the depth under the anode for Ge25Sb10S65 poled glass was determined using the analyze of remained second harmonic signal during the NaOH etching treatment. In parallel, a study of the concentration variation of elements being able to be involved in the formation of a charge space was achieved by using the secondary ion mass spectroscopy.
We present experimental results of thermal polings performed on Suprasil I samples (Heraeus) under square alternative voltages at various frequencies. We report a large increase (×5 compared to a continuous voltage poling) of the second order non-linear coefficient within a sample poled at 1mHz.
Chalcogenide glasses in the [Ge-Se-S-As] system have been synthesized and studied with respect to their nonlinear optical properties from third and second order. Z-scan and Mach Zehnder interferometry measurements of the nonlinear refractive index (n2) and nonlinear absorption ((beta) ) have been performed at 1064 nm. Some z-scan measurements have been also realized at 1430 nm. The results have been correlated to the structures of the glasses and the figure of merit has been calculated with the purpose of a potential utilization of these glasses in the realization of ultra- fast all-optical switches. Nonlinearities as high as 850 times the nonlinearity of silica glass have been obtained and some glasses exhibit at 1430 nm nonlinear optical characteristics suitable for telecommunication applications. The all-optical poling of a chalcohalogenide glass has been realized with a Q-switch mode-locked Nd:YAG laser at 1064 nm emitting 45 ps pulses at a repetition rate of 10 Hz with frequency doubling at 532 nm. A nonlinear coefficient deff equals 2.8 10-17 m/V similar to that of the reference glass Schott SF 57 has been obtained. The thermal poling of a chalcogenide glass also has been realized and a transient second order nonlinear susceptibility (chi) (2) has been observed.
Far-field properties of the optical power scattered from type IIA gratings photowritten within high NA germanosilicate fibers have been studied under various experimental conditions. First, the evolution of the out- coupling efficiency has been recorded in the course of the grating inscription. This revealed that the scattered power from fiber Bragg gratings sharply increased at the time of arrival of the type IIA photosensitivity. More, the out- coupling efficiency and the reflectivity of the type IIA grating seem to have a similar behavior under a thermal annealing process of the grating. It is then shown that the optical power detected in the far-field is scattered around a cone centered on the fiber axis, with a non-induced azimuthal distribution. The features of the observed pattern can be explained only if the UV induced index change, at the origin of he increase in the scattering efficiency, is non uniformly distributed in a plane perpendicular to the fiber axis.
A silicon film sandwiched between a sapphire substrate and a silver layer is used as a nonlinear optical
waveguide. The geometrical characteristics of the film and grating coupler have been optimized. This device has
been studied in the nonlinear regime using nanosecond and picosecond exciting pulses. Very fast switchings
are obtained which can be explained theoretically.