Corinne Felix

Absorption and fluorescence anisotropies of monoclinic crystals : the case of Nd:YCOB

We report for the first time measurements and modelization of the angular distributions of absorption and fluorescence in a monoclinic crystal. Studies on Nd:YCOB revealed specific topologies with ombilics. These new data upgrade the knowledge on low symmetry crystal optics.

Phase-matching directions, refined Sellmeier equations, and second-order nonlinear coefficient of the infrared Langatate crystal La 3 Ga 5.5 Ta 0.5 O 14

We directly measured phase-matching directions of second harmonic, sum, and difference frequency generations in the Langatate La₃Ga(5.5)Ta(0.5)O₁₄ (LGT) uniaxial crystal. The simultaneous fit of the data enabled us to refine the Sellmeier equations of the ordinary and extraordinary principal refractive indices over the entire transparency range of the crystal, and to calculate the phase-matching curves and efficiencies of LGT for infrared optical parametric generation.

Singular topology of optical absorption in biaxial crystals

We show for the first time that biaxial crystals exhibit continua of directions of propagation where the absorption coefficient is the same for the two associated polarization modes. This statement is supported by both calculations and experimental data obtained in Nd:YCOB.

Laser and self-doubling properties of a Nd:YCOB crystal cut as a sphere and inserted in a cavity

We propose what we believe to be for the first time a method for the direct characterization of the angular distribution of laser and self-doubling properties. It is based on the rotation of a sample cut as a sphere and inserted between two plane mirrors. We studied the monoclinic crystal Nd:YCOB. The only data that are mandatory to know are the crystal class and the orientation of the sphere in the dielectric frame.

Template-growth of periodically domain-structured KTiOPO(4) [Invited]

We performed the first growth, from a high temperature solution, of a 38.86 μm-periodicity PPKTP crystal of good optical quality over a thickness of more than 800 μm onto each of the two faces perpendicular to the c direction of a PPKTP substrate previously obtained by electric field poling. The quasi-phase matched second harmonic generation properties in the grown layer and substrate are similar and in accordance with calculation.

Laser optical feedback imaging insensitive to parasitic optical feedback

We present an optical architecture for the laser optical feedback imaging (LOFI) technique that makes it possible to avoid the effect of the optical parasitic reflections introduced by the optical components located between the laser source and the studied object. These reflections damage phase and amplitude information contained in the images. This phenomenon is a leading problem that strongly limits the LOFI performance for weak feedback detection. Consequently, it is essential to be able to limit or avoid the effect of these parasitic reflections to reach the optimal LOFI performance.

Energetic and spectral properties of triple photon downconversion in a phase-matched KTiOPO 4 crystal

We measured the spectrum and energy of infrared triple photons generated in a phase-matched KTiOPO4 crystal pumped by picosecond beams at 532 and 1662 nm. The experimental data are in good agreement with our model, taking into account the spectral linewidths of the incident beams as well as a parasitic Kerr effect.

Refractive indices, phase-matching directions and third-order nonlinear coefficients of rutile TiO2 from third harmonic generation

Experiments of third harmonic generation in rutile TiO2 allowed us to determine the phase-matching angles and the refractive indices of the crystal up to 4500 nm. We also showed that χ16 and χ18 coefficients of the third order electric susceptibility tensor exhibit opposite signs, and that |χ18(616.7nm)| = 9.7 × 10−20 m2V−2.

Rotation of the absorption frame as a function of the electronic transition in the Nd 3+ :YCa 4 O(BO 3 ) 3 monoclinic crystal

We report the first measurements of the angular distribution of absorption under polarized light corresponding to seven electronic transitions of Nd(3+) ions in the monoclinic crystal Nd:YCOB, revealing a rotation of the symmetry axes of the different patterns.

Angular quasi-phase-matching: theory and first experiments

Advances in the periodic poling process have led to longer and larger PPLN crystals. Today it is also possible to prepare PPLN samples with a thickness of about 5 mm which allows the use of pump laser beams with a larger aperture, and so with a higher energy. Moreover thicker samples give the possibility to consider quasi-phase-matching (QPM) at any angle with respect to the grating periodicity. We called this scheme angular quasi-phase-matching (AQPM). In order to illustrate the potentiality of AQPM, we compared its tunability and spectral acceptance with that of BPM in the case of second harmonic generation (SHG) and difference frequency generation (DFG) in the periodically poled negative uniaxial 5%MgO:PPLN crystal, with a grating periodicity Λ = 32.2 μm We found that AQPM exhibits complementary spectral range and acceptances compared with BPM. We experimentally performed the first validation of the theory of AQPM by cutting 5%MgO:PPLN as a polished sphere with a diameter of 3.9 mm in order to propagate beams in any direction of the crystal by keeping normal incidence. It allowed us to measure any SHG and DFG AQPM direction, with the associated efficiencies, the spectral and angular acceptances. They are reported with calculations.