Second harmonic generation in self-induced waveguides in Lithium Niobate

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Frequency-doubling in self-induced waveguides in lithium niobate

International audienceEfficient frequency-doubling is experimentally demonstrated in presence of beam self-trapping in congruent lithium niobate crystal. The self-trapping is induced by the generated second harmonic beam via photorefractive effect under an external applied field. The local space charge field distribution, formed by the second harmonic beam, is shown to efficiently trap both wavelengths. The dynamics of selffocusing is studied along with the power evolution of the second harmonic beam. Fast tuning of phase matching conditions in the written waveguide is realized by an externally applied voltage also used for the photorefractive confinement

Second harmonic generation in self-induced waveguides in Lithium Niobate

We present the investigation of second harmonic generation in congruent undoped lithium niobate crystal in presence of strong photorefractive and photovoltaic effect. We show that phase matching condition can be efficiently varied employing both the temperature and the electric field tuning. We also perform experiments on second harmonic generation with focused light, showing that the photorefractive effect is responsible for a strong distortion of the beam as well as a local modification of the phase matching condition. Finally, we demonstrate that an external bias can be used in order to switch from optical damage and distortion to self-confinement and guidance, reaching higher conversion efficiency through confinement and good overlap between interacting waves

3-D integrated optical interconnect induced by self-focused beam

International audienceThe realisation of a 1×4 optical integrated routing circuit is reported. The router is composed of multiple adjacent circular waveguides formed with self-focused beams by photorefractive effect inside a congruent photonic-grade lithium niobate wafer. The routing ability of the 3-D optical component is demonstrated and characterised

Self-induced waveguides created by second harmonic generation in Lithium Niobate

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Detection of fast flying nanoparticles by light scattering over a large volume

Detection of nanoparticles is of paramount importance for contamination control in ultra-clean systems. Light scattering is a well-known detection method which is applied in many different scientific and technology domains including atmospheric physics, environmental control, and biology. It allows contactless and remote detection of sub-micron size particles. However, methods for detecting a single fast moving particle smaller than 100 nm are lacking. In the present work we report a preliminary design study of an inline large area detector for nanoparticles larger than 50 nm which move with velocities up to 100 m/s. The detector design is based on light scattering using commercially available components. The presented design takes into account all challenges connected to the inline implementation of the scattering technique in the system: the need for the detector to have a large field of view to cover a volume with a footprint commensurate to an area of 100mm x 100mm, the necessity to sense nanoparticles transported at high velocity, and the requirement of large capture rate with a false detection as low as one false positive per week. The impact of all these stringent requirements on the expected sensitivity and performances of the device is analyzed by mean of a dedicated performance model