Insero, G.Clivati, C.D'Ambrosio, D.De Natale, P.Santambrogio, G.Schunemann, P, G.Borri, S.Zondy, Jean-Jacques2020-05-042020-05-042017-01-01Insero, G., Clivati, C., D’Ambrosio, D., De Natale, P., Santambrogio, G., Schunemann, P. G., Borri, S., & Zondy, J. J. (2017). Mid-infrared tunable, narrow-linewidth difference-frequency laser based on orientation-patterned gallium phosphide. Journal of Physics: Conference Series, 793, 12012. https://doi.org/10.1088/1742-6596/793/1/0120121742-658810.1088/1742-6596/793/1/012012https://iopscience.iop.org/article/10.1088/1742-6596/793/1/012012http://nur.nu.edu.kz/handle/123456789/4592We report on the first characterization of orientation-patterned gallium phosphide (OP-GaP) crystals used to generate narrow-linewidth, coherent mid-infrared (MIR) radiation at 5.85 μm by difference frequency generation (DFG) of continuous-wave (cw) Nd:YAG laser at 1064nm and diode-laser at 1301nm. By comparison of the experimental absolute MIR efficiency versus focusing to Gaussian beam DFG theory, we derive an effective nonlinear coefficient for first-order quasi-phase-matched OP-GaP at the generated DFG wavelength. Using d = (2/π)d 14 and taking into account Miller's delta rule, we retrieve an absolute value of the d 14 quadratic nonlinear susceptibility coefficient of GaP of d 14 = 27.2(3) pm/V at 5.85 μm, in good agreement with the latest absolute measurement of this nonlinear coefficient from non-phase-matched second-harmonic generation (1.32 μm → 0.66 μm) taking into account multiple reflection effects [Shoji et al 1997 J. Opt. Soc. Am. B 14 2268]. The temperature and signal-wave tuning curves are also in qualitative agreement with a recently proposed temperature-dependent Sellmeier equation for OP-GaP when focusing effects are taken into account.enAttribution-NonCommercial-ShareAlike 3.0 United Stateswaist measurementsgallium phosphidedifference frequency generationDFGcoherent mid-infraredOP-GaPMIRResearch Subject Categories::NATURAL SCIENCES::PhysicsArticle