Mid-infrared tunable, narrow-linewidth difference-frequency laser based on orientation-patterned gallium phosphide
Authors: Insero G., Clivati C., D\’Ambrosio D., De Natale P., Santambrogio G., Schunemann P.G., Borri S., Zondy J.J.
Autors Affiliation: Istituto Nazionale di Ottica, INO-CNR, European Laboratory for Nonlinear Spectroscopy, LENS, via N. Carrara 1, Sesto Fiorentino, 50019, Italy; Istituto Nazionale di Fisica Nucleare, INFN, Sezione di Firenze, via G. Sansone 1, FI, Sesto Fiorentino, 50019, Italy; Istituto Nazionale di Ricerca Metrologica, INRIM, Strada delle Cacce 91, Torino, 10135, Italy; BAE Systems, Inc., MER15-1813, P.O. Box 868, Nashua, NH 03061-0868, United States; Nazarbaev University, School of Science and Technology, Physics Department, Kabanbay Batyr 53, Astana, 010000, Kazakhstan
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 5.85µ 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 d = (1/2)x(2) eff=17(3) pm/V for first-order quasi-phase-matched OP-GaP at the generated DFG wavelength. Using d = (2/p)s14and taking into account Millers delta rule, we retrieve an absolute value of the d14quadratic nonlinear susceptibility coefficient of GaP of d14 = 27.2(3) pm/V at 5.85 µ, in good agreement with the latest absolute measurement of this nonlinear coefficient from non-phase-matched second-harmonic generation (1.32 µ ? 0.66 µ) 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.
More Information: The ELI European project; Instituto Nazionale di Fisica Nucleare (INFN) (SUPREMO); Horizon 2020 (EMPIR-15SIB05-OFTEN); Participating Sates.KeyWords: Crystal orientation; Gallium alloys; Gaussian beams; Infrared devices; Neodymium lasers; Nonlinear optics; Optical frequency conversion; Phase matching; Semiconducting gallium, Absolute measurements; Difference frequency; Difference-frequency generation; Effective nonlinear coefficient; Multiple reflections; Nonlinear coefficient; Quadratic nonlinear susceptibility; Temperature dependent, Gallium phosphide