1,721,002 research outputs found
Ir low dispersion soliton waveguides written with low power lasers
No full textWe show that soliton waveguides written in the volume of lithium niobate crystals with low power continuous wave lasers in green - blue spectral domain have low dispersion in guiding ultrashort (femtosecond) pulses of infrared light. We analyze different components of dispersion and their contribution to the total dispersion of these soliton waveguides. Our experimental results obtained in guiding near infrared ultrashort pulses confirm the theoretical predictions
3D-soliton waveguides in lithium niobate for femtosecond light pulses
No full textWe show that efficient waveguides can be written by bright spatial solitons in the volume of lithium niobate photorefractive crystals by cw and pulsed laser beams. Using high-repetition-rate femtosecond laser pulses, an efficient formation of soliton waveguides (SWGs) is possible, after accumulating a large number of pulses, because the characteristic photorefractive build-up time is much longer than the pulse period and the efficient two-photon absorption may contribute to the solitonic confinement. These results open the possibility of writing reconfigurable single SWGs and SWG arrays (with any spatial orientation and large range of periods) and optimally guiding the femtosecond pulsed laser beams through them, creating a graded refractive-index profile matched to the spatial beam profile. Our experiments also show a small increase in pulse duration (small dispersion) in these waveguides
Arrays of soliton waveguides in lithium niobate for parallel coupling
No full textLithium niobate is a promising material for all-optical integrated photonics, particularly for soliton waveguides. An array of 13 x 10 soliton waveguides has been induced in a lithium niobate crystal using c.w. laser light at 532 nm wavelength. The spatial separation between waveguides (100 pm) ensures soliton writing without interactions, avoiding the possible deformation of soliton channels over a long distance (more than 15 diffraction lengths) and allowing the individual addressing of each soliton waveguide. The coupling and guiding properties of this parallel optical coupler at different wavelengths, with c.w. and pulsed laser signals, are investigated
Fast writing of soliton waveguides in lithium niobate with a low-power blue-violet laser
No full textWe report soliton waveguide creation in lithium niobate crystals with 405nm c.w. radiation from a low-cost blue-violet laser diode. The high photorefractive sensitivity of lithium niobate at this wavelength allows fast soliton waveguide writing with low light power (~40nW). The writing process of soliton waveguides at this wavelength is experimentally studied. We also show the convenient writing of soliton waveguides arrays in the crystal volume and the good propagation of femtosecond pulses (at 1030 nm) through these waveguides. These waveguides are good candidates for all-optical integrated photonics
Analysis of soliton waveguides in lithium niobate at 405 nm wavelength
No full textRecently it was shown that soliton waveguides in lithium niobate can be recorded very fast at 405 nm wavelength. We analyze the mode profile of soliton waveguides recorded at 405 nm using different external electric fields and different writing beam polarizations. We discuss the advantages of recording at this wavelength when comparing with the recording process at 532 nm. © 2013 SPIE
Complete characterization of (2+1)D soliton formation in photorefractive crystals with strong optical activity
No full textWe analyse the (2 + 1)D soliton formation in photorefractive crystals with strong optical activity. The complete characterization of a soliton in such a crystal requires a careful determination of its polarization state. In fact, even if the beam experiences an homogeneous propagation, the polarization dynamics require it to reach a well defined state which has been identified on the Poincare sphere. Experimental results for the soliton intensity profile and for its polarization dynamics are in good agreement with numerical simulations
Polarization evolution of spatial solitons in photorefractive crystals with large optical activity
No full textWe present the first investigation of bright screening soliton formation in Erbium doped lithium niobate grown by the Czochrlaski technique (0.7% mol.). We analyse the formation of two-dimensional spatial soliton and study its long term stability. Measurements of photovoltaic current show that presence of erbium in the lattice cause an increase of the current density. Both dynamic of soliton formation and photovoltaic measurements indicates a lower NA content in erbium doped samples compared to undoped samples
Z-Scan measurement of thermal optical nonlinearities
No full textThe thermal third order nonlinearity of a neutral density glass is measured using the Z-Scan method. The measurements are performed using two different laser configurations: a continuous wave laser at 532 nm and a femtosecond laser at 1060 nm. The measurements are used to determine the nonlinear refractive index, n 2 and the thermo-optical coefficient dt dn of the samples. The measurements in the two different laser configurations are in good agreement with the existing theory models
Soliton waveguides in photorefractive crystals
No full textThe spatial solitons can create reversible or irreversible single-mode waveguides in the propagating mateials. The importent features ere the 3D orientation end graded index profile matched to the laser fuadamental mode. Bright spatial solitons are theoretically demonstrated and expaimeitally observed in the propagation of laser beams in widely available faotorefractive crystals such as Bi12 SiO20 (BSO) and LiNbO3 (LN). We show the first observation of waveguiding by screening-photovoltaic bright solitons in LN and the low absorption and dispersion of the corresponding light produced waveguides (with femtosecond laser pulses). Applications in high coupling efficiency, adaptive optical interconnections and photonics crystal production are possible
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