Photorefractive screening-photovoltaic solitons are observed in lithium niobate. Two-dimensional bright circular solitons are formed thanks to a strong static bias field, externally applied, opposite to the photovoltaic internal field. The dynamics of the soliton formation is monitored and compared to a time-dependent numerical model allowing determination of the photovoltaic field. Efficient single mode waveguides are shown to be memorized by the soliton beam for a long time. (C) 2004 American Institute of Physics

No abstract

We report the measurements of picometer vibration amplitudes produced by a piezo mirror in an interferometric setup, using a GaAs:Cr photoconductive device. The moving light fringes (gratings) induce in this new detector periodic photocurrents characterized by efficient suppression of the low-frequency drifts of the working point and low sensitivity to the amplitude laser noise. The optimum operation conditions of this system are also shown.

No abstract

No abstract

The light emission properties of the complex formed from deoxyribonucleic acid (DNA)-cetyltrimethylammonium chloride (CTMA) surfactant doped with different concentrations of Rhodamine 610 (Rh610) dye and dissolved in butanol are investigated and discussed. The results are compared to those obtained when only the Rh610 dye is dissolved in butanol, at the same concentrations. The light emission is excited in the investigated samples by the nanosecond pulses of a frequency-doubled Nd:YAG laser, at a wavelength of 532 nm. We have demonstrated the lasing effect in the investigated complex and we have studied its efficiency and coherence properties. The lasing properties of the Rh610 dye are favourably influenced by the presence of the DNA-CTMA complex in the investigated compound. It leads to an increase in the lasing efficiency and in the slope efficiency. Also the temporal coherence of the emitted light is larger and the emission can be tuned to shorter wavelengths.

In this work, we report on an experimental investigation of the nonlinear optical properties near the first electronic resonance of thiol-capped CdTe quantum dots (QDs) being in the strong confinement regime. Using a cw laser excitation in a Z-scan experimental setup, we show the presence of saturated Kerr-type nonlinear optical properties of the QDs, at low intensity levels. The large optical nonlinearity and the control of the linear and nonlinear optical properties by the size of the QDs are of special interest for applications in integrated nanophotonic devices.

(2+1)-dimensional spatial solitons in Bi12SiO20 (BSO) photorefractive crystals with large optical activity are experimentally demonstrated. The soliton formation when a Gaussian beam is injected at the input has been previously analyzed numerically and then experimentally investigated. We demonstrate analytically, numerically, and experimentally that by applying static electric biases of high values, the polarization rotation accelerates: this acceleration prevents the beam from broadening if the polarization rotation period becomes shorter than the diffraction length. Contemporary to this nonlinear optical activity, an induced birefringence affects the beam polarization state. Analysis of the polarization dynamics shows that the polarization changes nonuniformly across the beam (with a field dependent speed) until about 30-35 kV/cm; above this limit, the whole beam has just one polarization state. Representation on the Poincaré sphere of the polarization dynamics reveals the existence of a stable polarization trajectory closed around a polarization attractor that depends on the linear optical activity and on the photorefractive nonlinearity. The experimental soliton is well described by the analytical solutions already obtained [Fazio et al., Phys. Rev. E 66, 016605 (2002)].