Mid-infrared tunable, narrow-linewidth difference-frequency laser based on orientation-patterned gallium phosphide

Giacomo Insero, Cecilia Clivati, Davide D’Ambrosio, Paolo De Natale, Gabriele Santambrogio, Peter G. Schunemann, Simone Borri, J.‐J. Zondy

2017

Full text Open access: Gold Metadata (CSL-JSON)
DOI 10.1088/1742-6596/793/1/012012
Data confidence 70 medium
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Abstract

We 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.