**11** Publications

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Opt Lett 2020 Nov;45(21):6026-6029

We worked on a new scheme of quasi-phase matching (QPM) based on the negative first order of the spatial modulation of the sign of the second-order nonlinearity. Applying this scheme in the case of angular-QPM (AQPM) in a biaxial crystal reveals new directions of propagation for efficient parametric frequency conversion as well as "giant" spectral acceptances. The experimental validation is performed in a periodically poled rubidium-doped biaxial crystal. This new approach naturally extends to other periodically poled uniaxial crystals such as periodically poled .

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http://dx.doi.org/10.1364/OL.408839 | DOI Listing |

November 2020

Opt Lett 2018 Sep;43(17):4276-4279

We report the first experimental validation of angular quasi-phase-matching (AQPM) theory in a biaxial crystal by performing second-harmonic generation (SHG) in the periodically-poled Rb-doped KTiOPO (PPRKTP) crystal cut as a sphere. Both AQPM and birefringence phase-matching (BPM) angles were measured thanks to a Kappa circle.

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http://dx.doi.org/10.1364/OL.43.004276 | DOI Listing |

September 2018

Opt Lett 2018 Apr;43(8):1818-1821

We performed the direct measurement of second harmonic generation and sum frequency generation phase-matching directions in the organic N-benzyl-2-methyl-4-nitroaniline crystal over its visible and near-infrared transparency range. The fit of these data allowed us to refine the Sellmeier equations of the three principal refractive indices in this range. With these equations, we improved the calculated tuning curves of terahertz emission from a phase-matched difference frequency process. We also determined the absolute magnitude of the d nonlinear coefficient.

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http://dx.doi.org/10.1364/OL.43.001818 | DOI Listing |

April 2018

Opt Lett 2016 Nov;41(22):5290-5293

We directly measured the phase-matching properties of the biaxial GdCa_{4}O(BO_{3})_{3} (GdCOB) crystal using the sphere method. We studied second-harmonic generation and difference frequency generation in two principal planes of the crystal. All these data allowed us to refine the Sellmeier equations of the three principal refractive indices. These equations are valid over the entire transparency range of GdCOB and then could be used to calculate the tuning curves of infrared optical parametric generation.

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http://dx.doi.org/10.1364/OL.41.005290 | DOI Listing |

November 2016

Opt Lett 2015 Oct;40(20):4591-4

We performed a complete study of angle noncritical phase-matched second-harmonic generation in BaGa4Se7 in the mid-infrared region. We measured the dielectric frame orientation and showed that it does not rotate as a function of wavelength. We determined the phase-matching wavelengths and the associated spectral and angular acceptances along the x and y axes of the dielectric frame. We also estimated the magnitude of the nonlinear coefficients involved.

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http://dx.doi.org/10.1364/OL.40.004591 | DOI Listing |

October 2015

Opt Lett 2014 Jul;39(13):4033-6

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.

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http://dx.doi.org/10.1364/OL.39.004033 | DOI Listing |

July 2014

Opt Express 2013 Nov;21(23):28886-91

We conceived a unique fully parametric source based on two independent cylindrical OPOs simultaneously pumped by the same Nd:YAG laser. Each OPO delivers more than 2 mJ and is continuously tunable between 1.41 µm and 4.3 µm. This source is of particular interest for the study of the generation of infrared parametric light in nonlinear crystals. It was validated by performing difference frequency generation experiments in CdSe crystals with output in the range 8 - 10 µm.

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http://dx.doi.org/10.1364/OE.21.028886 | DOI Listing |

November 2013

Chemphyschem 2014 Jan 2;15(1):118-25. Epub 2013 Dec 2.

Institut Charles Gerhardt Montpellier, UMR 5253, CNRS-UM2-ENSCM-UM1, C2M, Université Montpellier 2, CC 1504, Place Eugène Bataillon, 34095 Montpellier Cédex 5 (France), Fax: (+33) 467144290.

From high-precision Brillouin spectroscopy measurements, six elastic constants (C11, C33, C44, C66, C12, and C14) of a flux-grown GeO2 single crystal with the α-quartz-like structure are obtained in the 298-1273 K temperature range. High-temperature powder X-ray diffraction data is collected to determine the temperature dependence of the lattice parameters and the volume thermal expansion coefficients. The temperature dependence of the mass density, ρ, is evaluated and used to estimate the thermal dependence of its refractive indices (ordinary and extraordinary), according to the Lorentz-Lorenz equation. The extraction of the ambient piezoelectric stress contribution, e11, from the C'11-C11 difference gives, for the piezoelectric strain coefficient d11 , a value of 5.7(2) pC N(-1), which is more than twice that of α-quartz. As the quartz structure of α-GeO2 remains stable until melting, piezoelectric activity is observed until 1273 K.

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http://dx.doi.org/10.1002/cphc.201300793 | DOI Listing |

January 2014

Opt Lett 2013 Mar;38(6):860-2

Institut Néel Centre National de la Recherche Scientifique-Université Joseph Fourier, Grenoble, France.

A 5 mm thick and 38 mm long 5% MgO-doped periodically poled lithium niobate (MgO:PPLN) cylinder with a grating period of 28 μm has been engineered as a partial cylinder with an angular aperture of 45°. An optical parametric oscillator based on this crystal and pumped at 1.064 μm is reported. The output energy is comparable to that generated in the same kind of sample cut as a slab, but the wavelength tunability from 1.41 to 4.3 μm is much broader and continuous.

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http://dx.doi.org/10.1364/OL.38.000860 | DOI Listing |

March 2013

Opt Lett 2011 May;36(10):1800-2

Institut Néel Centre National de la Recherche Scientifique - Université Joseph Fourier, 25 Rue des Martyrs, BP 166, F38402 Grenoble Cedex 9, France.

We directly measured the second harmonic generation and difference frequency generation phase-matching directions of the nonlinear crystal CdSiP(2) until 9.5 μm using the sphere method. The simultaneous fit of the experimental angular data allowed the Sellmeier equations of the ordinary and extraordinary principal refractive indices to be refined over the entire transparency range of the crystal.

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http://dx.doi.org/10.1364/OL.36.001800 | DOI Listing |

May 2011

Inorg Chem 2010 Oct;49(20):9470-8

Institut Charles Gerhardt Montpellier, UMR-CNRS-UM2-ENSCM-UM1 5253, Université Montpellier 2, Equipe C2M, Place E. Bataillon, 34095 Montpellier, Cedex 5, France.

Experimental and theoretical studies have been performed to demonstrate the high performance of the novel piezoelectric material GaAsO(4). Hydrothermally grown single crystals of α-quartz phase GaAsO(4) were studied by Brillouin spectroscopy to determine elastic constants. Experimentally obtained values of C(11), C(66), C(33), C(44), C(14) and C(12) are 59.32, 19.12, 103.54, 30.70, 1.7, and 21.1 GPa, respectively. Elastic and piezoelectric tensors were also calculated by a first principles method in this work, leading to a very good agreement with experimental results and confirming the values of elastic components obtained indirectly such as C(14) and the negligible piezoelectric correction for C(11). The thermal behavior of the elastic constant corresponding to the [100] longitudinal L mode (C(11)) was studied up to 1137 K to estimate potential piezoelectric performance. It was found that the thermal behavior is linear up to 1273 K which is just below the thermal decomposition temperature of 1303 K. High thermal stability can be linked to the higher polarizability of large cations Ga and As because of neighboring oxygen atoms. On the basis of thermal behavior, GaAsO(4) is a promising material for high temperature piezoelectric applications.

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http://dx.doi.org/10.1021/ic1011499 | DOI Listing |

October 2010