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We have performed a pure optical frequency measurement of the $2S\ensuremath{-}12D$ two-photon transitions in atomic hydrogen and deuterium. From a complete analysis taking into account this result and all other precise measurements (by ourselves and other authors), we deduce optimized values for the Rydberg constant, ${R}_{\ensuremath{\infty}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}109737.31568516(84){\mathrm{cm}}^{\ensuremath{-}1}$ (relative uncertainty of $7.7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}12}$) and for the $1S$ and $2S$ Lamb shifts ${L}_{1S}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}8172.837(22)\mathrm{MHz}$ and ${L}_{2S\ensuremath{-}2P}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1057.8446(29)\mathrm{MHz}$ [respectively, ${L}_{1S}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}8183.966(22)\mathrm{MHz}$, and ${L}_{2S\ensuremath{-}2P}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1059.2337(29)\mathrm{MHz}$ for deuterium]. These are now the most accurate values available.

We report on dynamical signatures of signal/idler self phase-locking in a cw frequency divide-by-three optical parametric oscillator subject to two competing chi(2) nonlinear processes, confirming the theoretical predictions

We report on preliminary performance of a mid-IR doubly-resonant difference frequency (DFG) spectrometer generating 30 nW of 10.2-/spl mu/m tunable radiation out of 7 mW and 275 mW of the diode laser pump inputs at 778 nm and 842 nm.

Thermal lensing and dephasing are evidenced to be responsible of the output power saturation of continuous-wave (cw) doubly/triply resonant mid-IR silver gallium sulfide parametric oscillators. The threshold for oscillation is critically dependent on the cavity geometry. A theoretical TRO model including thermally induced Kerr effect is introduced to account for the observed power limitation to the milliwatt range.

Lithium thioindate (LiinS2) nonlinear single crystals were doped with Nd3+ ions and their spectroscopic properties were studied at 80K and 300K. Thanks to its unextended phonon spectrum with v < 400cm·−1 Nd:LilnS2 crystals are expected to have luminescence in the 1 to 5 μm region as a result of radiative transitions between sub levels of the ground 4I manifold. We also report the first observation of a phase-matched second-harmonic generation in the undoped material, using a nanosecond-GPO that is tunable in the range 2.4 - 2.6μm as the pump source. A preliminary vafoe of the type-II nonlinearity yields deff(XY)=3.4pm/V.

We report on preliminary results of a dual-cavity difference-frequency spectrometer generating 30 nW of 10.2-μm tunable radiation out of 7 mW (778 nm) and 275 mW (842 nm) AlGaAs diode laser pump inputs. This device will be used to perform high- resolution saturation spectroscopy in the 9-11μm range, for optical frequency metrology applications.

Second harmonic generation (SHG) of a KCl:Li color center laser, up-conversion (SFM) of a near-IR AlGaAs diode laser by a CO2 laser and non-critical (3ω-ω → 2ω) temperature tuned difference frequency generation (DFG) are reported using silver thiogallate. These parametric processes participate in a frequency chain synthesizing the 13th harmonic of a CO2/OsO4 reference optical standard at 29 THz (10.11µm).

We report the temperature dependence of a continuous-wave noncritically phase-matched (θ=90°) optical parametric amplifier based on a 15-mm-long silver gallium sulfide crystal (AgGaS2) pumped by a 50-mW near-IR AlGaAs diode laser (λ3=0.843 µm). This amplifier is idler seeded by a 15-mW KCl:Li (FA-II) color-center laser (λ1=2.53 µm) and produces microwatt-range power of a signal radiation at λ2=1.265 µm. Updated linear and thermo-optic data of this chalcopyrite material, such as its room-temperature refractive indices and their temperature dependence, are devised from this type I (eoo) 3:1 frequency-division process and from other published data on noncritically phase-matched difference-frequency generation. The resulting dno,e/dT values reproduce fairly well all of the reported results on temperature phase-matched parametric mixing.