Widely tunable near-infrared optical parametric oscillator based on a 5%MgO:PPLN partial cylinder pumped at 1064†nm by a 1-kHz sub-nanosecond microchip laser.

We report the implementation of a singly resonant optical parametric oscillator using a 5%MgO:PPLN partial cylinder pumped by a sub-nanosecond microchip laser emitting 1064 nm at a repetition rate of 1 kHz. It is continuously tunable from 1410 nm up to 4330 nm by rotating the cylinder and a total energy of several microjoules is emitted with a beam quality factor M2 lower than 3.

Second-order nonlinear optical coefficients of the monoclinic crystal BaGa4Se7.

We characterize the magnitude and relative signs of the second-order nonlinear optical coefficients of the biaxial crystal BaGa4Se7 (BGSe) combining measurements of phase-matched and non-phase-matched second-harmonic generation at different wavelengths using slabs and a sphere.

Birefringence phase-matched direct third-harmonic generation in a ridge optical waveguide based on a KTiOPO4 single crystal.

Birefringence phase-matched third-harmonic generation at 1594 nm is performed for the first time in a KTiOPO4 single crystal micrometric ridge waveguide. The energy conversion efficiency reaches 3.4% for a pump energy as low as 2 µJ over a pulse duration of 15 ps at a repetition rate of 10 Hz. Strong agreements between theory and experiments for both phase-matching and conversion efficiency is obtained, which let us envision future triple photon generation quantum experiments.

Development and experimental demonstration of negative first-order quasi-phase matching in a periodically poled Rb-doped KTiOPO4 crystal.

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 KTiOPO4 biaxial crystal. This new approach naturally extends to other periodically poled uniaxial crystals such as periodically poled LiNbO3.

Focus issue introduction: advanced solid-state lasers.

This joint issue of Optics Express and Optical Materials Express features 28 state-of-the-art articles written by authors who participated in the international "Advanced Solid State Lasers" conference, held in Boston November 4-8, 2018. This review provides a summary of these articles that cover the spectrum of solid state lasers from materials research to sources and from design innovation to applications.

Feature issue introduction: Advanced Solid-State Lasers 2017.

The Advanced Solid State Lasers 2017 Conference (ASSL) was held from October 1 to 5, 2017. It was an extraordinary conference at the Nagoya Congress Center in Nagoya, Japan. ASSL 2017 again suggested an impressive platform where miscellaneous perceptions with a variety of approaches to optics, photonics, sensing, laser technology, laser systems, and solid state lasers were presented. This international meeting was highly selective, leading to high level contributions through one plenary conference, 17 invited presentations, 70 regular talks, and 121 posters. The present joint issue of Optics Express and Optical Materials Express features 27 articles written by ASSL 2017 authors and covering the spectrum of solid-state lasers from materials research to sources, and from design innovation to applications.

Phase-matched second-harmonic generation in a flux grown KTP crystal ridge optical waveguide.

Type II second-harmonic generation was performed in a 15.8-mm-long KTiOPO4 (KTP) micrometric ridge waveguide with an average transversal section of 38 µm2. Theoretical predictions are compared with experiments. Strong agreements are obtained for both phase-matching wavelengths and second-harmonic intensity. This work opens wide perspectives for integrated parametric optics.

Quadratic nonlinear optical properties of the organic N-benzyl-2-methyl-4-nitroaniline (BNA) biaxial crystal.

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 d24 nonlinear coefficient.

Validation of the angular quasi-phase-matching theory for the biaxial optical class using PPRKTP.

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 KTiOPO4 (PPRKTP) crystal cut as a sphere. Both AQPM and birefringence phase-matching (BPM) angles were measured thanks to a Kappa circle.

Study of middle infrared difference frequency generation using a femtosecond laser source in LGT.

We demonstrate phase-matched difference frequency generation in the emerging nonlinear crystal La3Ga5.5Ta0.5O14. Tunable wavelengths between 1.4 and 4.7 µm are generated by using femtosecond sources. We also report on the measurements of the optical damage threshold in the femtosecond regime and on the nonlinear refractive index n2.

Acentric langanite La3Ga5.5Nb0.5O14 crystal: a new nonlinear crystal for the generation of mid-infrared parametric light.

The mid-infrared spectral range extending from 2 to 6 µm is significant for scientific and technological applications. A promising nonlinear oxide crystal La3Ga5.5Nb0.5O14 (LGN) is proposed and fully characterized for the first time to our knowledge. The transparency range extends between 0.28 and 7.4 µm. The two principal refractive indices were measured and we found that the nonlinear coefficient d11 = 3.0 ± 0.1 pm/V at 0.532 µm. The simultaneous fit of data allowed us to refine the Sellmeier equations of LGN and to calculate the tuning curves for optical parametric generation (OPG) pumped at 1.064 µm. Calculations are consistent with recorded data and also show the generation of a supercontinuum between 1.5 and 3.5 µm when pumped at 0.98 µm by a Ti:Sapphire laser.

Dielectric frame, Sellmeier equations, and phase-matching properties of the monoclinic acentric crystal GdCa4O(BO3)3.

We directly measured the phase-matching properties of the biaxial GdCa4O(BO3)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.

Phase-matching directions and refined Sellmeier equations of the monoclinic acentric crystal BaGa4Se7.

We directly measured the phase-matching directions of second-harmonic and difference frequency generation in the principal planes of the biaxial BaGa4Se7 (BGSe) crystal using the sphere method. The simultaneous fit of the data allowed us to refine the Sellmeier equations of the three principal refractive indices of BGSe, and to calculate the tuning curves for infrared optical parametric generation.

Anisotropy analysis of third-harmonic generation in a germanium-doped silica optical fiber.

We performed an intermodal third-harmonic generation around 516 nm in a germanium-doped silica optical fiber. The analysis of the complex polarization behavior that was observed allowed us to determine the orientation symmetry group of the fiber and the relative values of the independent coefficients of the third-order electric susceptibility tensor.

Angle noncritical phase-matched second-harmonic generation in the monoclinic crystal BaGa4Se7.

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.

Phase-matching directions, refined Sellmeier equations, and second-order nonlinear coefficient of the infrared Langatate crystal La3Ga(5.5)Ta(0.5)O14.

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.

Social desirability, dietary intakes, and variables related to attitudes and behaviours towards eating among French-speaking adults from Quebec, Canada: The PREDISE study.

The primary objective of this study was to examine how social desirability is associated with self-reported measures of dietary intakes and variables related to attitudes and behaviours towards eating. This analysis was conducted in 1083 adults (50.0% women) from the PREDISE study. Social desirability was assessed using the Balanced Inventory of Desirable Responding (BIDR) questionnaire, which includes two subscales: (1) self-deceptive enhancement (SDE), i.e., having an overly positive self-image and (2) impression management (IM), i.e., intentional response distortion to please. BIDR total score and IM subscore were positively associated with the Canadian Healthy Eating Index (C-HEI) (ß = 0.24 and ß = 0.50; p ≤ 0.0003), calculated using data from three self-administered 24 h food recalls. All BIDR scores were positively associated with self-determined motivation for eating regulation (0.03 ≤ ß ≤ 0.06; p < 0.0001), measured by the Regulation of Eating Behavior Scale, and with the intuitive eating score (0.02 ≤ ß ≤ 0.05; p < 0.0001). Also, all BIDR scores were negatively associated with hunger and disinhibition scores measured by the Three-Factor Eating Questionnaire (-0.17 ≤ ß ≤ -0.09; p < 0.0001). All these associations were adjusted for age, sex, BMI, and the education level. Furthermore, controlling for both dimensions of social desirability did not impact the magnitude of the association between self-determined motivation (the strongest predictor of healthy eating in the PREDISE study) and C-HEI. According to our results, associations are observed with diet quality, as well as with attitudes and behaviours towards eating; therefore, a measurement of social desirability responding would be pertinent in studies using those or related variables.

A latent profile analysis based on diet quality and eating behaviours in participants of the PREDISE study characterized by a higher BMI.

The aim of this study was to identify eating-related latent profiles based on diet quality and eating behaviours within a population characterized by a body mass index (BMI) of at least 25 kg/m2, and to compare metabolic variables between profiles. This analysis was conducted in a sample of 614 adults (45.6% women; 44.8 ± 12.9 years) from the cross-sectional PREDISE study. Participants completed the Three-Factor Eating Questionnaire, the Intuitive Eating Scale-2, the Regulation of Eating Behavior Scale, and three self-administered 24 h food recalls. Waist circumference, blood lipids, blood pressure, and fasting glucose were measured to identify carriers of the metabolic syndrome. A latent profile analysis was performed, and cases of metabolic syndrome were compared between profiles. A three-profile solution was found. Profile 1 (22.8%) was characterized by lower diet quality, lower self-determined motivation for eating, lower restraint, and higher intuitive eating. Profile 2 (44.5%) was characterized by higher diet quality, higher self-determined motivation for eating, higher restraint, lower disinhibition, and higher intuitive eating. Profile 3 (32.7%) was characterized by intermediate diet quality, higher non-self-determined motivation for eating, higher restraint and disinhibition, and lower intuitive eating. We found fewer cases of metabolic syndrome among participants in profile 2 than in the other profiles (p = 0.0001). This study suggests that a profile characterized by a lower disinhibition and higher levels of restraint, intuitive eating, self-determined motivation, and diet quality is associated with a better metabolic health among individuals with a higher BMI.

Dual-wavelength source from 5%MgO:PPLN cylinders for the characterization of nonlinear infrared crystals.

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.

Experimental demonstration of five-beam-pumped optical parametric amplification.

We experimentally demonstrated optical parametric amplification with five pumps coming from two different oscillators. By spreading those partially mutually incoherent pumps at 532 nm over different phase-matching directions around a signal at 725 nm, we obtained a pumps-to-signal efficiency of 27%.