Kiyoshi Kato

Sellmeier and thermo-optic dispersion formulas for KTP

KTP has been found to be phase matchable for type-2 second-harmonic generation of the third harmonics of the CO2 laser wavelengths at 9.2714 and 9.5525 microm at 20.0 degrees C. The resulting angle and temperature-tuning data combined with the literature values of the Nd:YAG laser-pumped optical parametric oscillator were used to improve the Sellmeier equations and the thermo-optic dispersion formula that reproduce well the temperature-tuned 90 degree phase-matching conditions of the flux-grown crystals. Applications to quasi phase matching are presented.

New data on the nonlinear optical constant, phase-matching, and optical damage of AgGaS2

The nonlinear optical constant of AgGaS2 was determined to be d36 (AgGaS2)=(0.84 ±0.1) ×d36 (AgGaSe2) =(34.8 ±4) pm/V from the direct comparison of the second-harmonic generation conversion (SHG) efficiencies of a CO2 laser at 9.2714 µm observed in AgGaSe2 under the identical experimental conditions. The phase-matching conditions for type-1 SHG in both AgGaS2 and AgGaSe2 are presented together with the damage thresholds at 9.2714 µm and 2.097 µm.

Solar-pumped 80 W laser irradiated by a Fresnel lens

A solar-pumped 100 W class laser that features high efficiency and low cost owing to the use of a Fresnel lens and a chromium codoped neodymium YAG ceramic laser medium was developed. A laser output of about 80 W was achieved with combination of a 4 m(2) Fresnel lens and a pumping cavity as a secondary power concentrator. This output corresponds to 4.3% of conversion efficiency from solar power into laser, and the maximum output from a unit area of Fresnel lens was 20 W/m(2), which is 2.8 times larger than previous results with mirror-type concentrator.

90 degrees phase-matched third-harmonic generation of CO(2) laser frequencies in AgGa(1-x)In(x)Se(2).

AgGa(1-x) In(x)Se(2) with x=0.474 was found to be 90 degrees phase matchable for third-harmonic generation of CO(2) laser wavelengths 9.2714-10.5910 mum by means of temperature tuning. Sellmeier equations and the thermo-optic constant for this crystal are presented.

90? Phase-Matching Properties of YCa4O(BO3)3 and GdxY1-xCa4O(BO3)3

YCa4O(BO3)3 has been found to be 90° phase-matchable for type-1 second-harmonic generation at 0.4168 µm along the z-axis at 20°C. The improved Sellmeier equations of YCa4O(BO3)3 that correctly reproduce our new experimental data for second-harmonic and sum-frequency generation in the 0.3547–1.9079 µm range are reported. In addition, the 90° phase-matching properties of GdxY1-xCa4O(BO3)3 as a function of the Gd molar concentration X are presented together with the empirical index formula.

200-mW-average power ultraviolet generation at 0.193 μm in K 2 Al 2 B 2 O 7

K2Al2B2O7 has been found to be phase matchable for type-1 sum-frequency generation (SFG) at 0.193 microm by mixing the Nd:YAG laser wavelength at 1.0642 microm and the SFG output of the RbTiOAsO4 optical parametric oscillator tuned at 0.2358 microm. An average power of 200 mW at 10 kHz was obtained in a 7-mm-long crystal. In addition, the Sellmeier equations and the thermo-optic dispersion formula, which predict well the phase-matching conditions and temperature phase-matching bandwidths (FWHM) for second-harmonic generation and SFG in the 0.193-0.669-microm range, are presented.

Thermo-optic dispersion formula for AgGaS 2

AgGaS(2) has been found to be 90 degrees phase matchable at 192 degrees C for sum-frequency mixing between the output of the KTP parametric oscillator at 3.2627 microm and its pump source at 1.0642 microm. The thermo-optic dispersion formula that can be used for good reproduction of the temperature-dependent phase-matching conditions thus far reported in the literature as well as our new data for second-harmonic generation of a CO(2) laser and its harmonics at 1.7652-5.2955 microm is presented.

Sellmeier and thermo-optic dispersion formulas for GaSe (Revisited)

This paper reports high-accuracy Sellmeier and thermo-optic dispersion formulas for GaSe that provide excellent reproduction of the phase-matching conditions for second-, third-, and fourth- harmonic generation of CO2 laser radiation at 10.5910 μm in the 20°C-200°C range as well as the data points of Feng et al. [Opt. Express16, 9978 (2008)10.1364/OE.16.009978OPEXFF1094-4087] for second-harmonic generation of CO2 laser radiation at 9.5862 μm and an Er3+:YSGG laser at 2.7960 μm in the -165°C-230°C range.

Phase-matched pure χ (3) third-harmonic generation in noncentrosymmetric BiB 3 O 6

Third-harmonic generation (THG) has been investigated in the monoclinic BiB3O6. The symmetry and birefringence analysis revealed that there are phase-matching conditions for the direct third-order nonlinear process, where the cascading second-order processes are precluded by the zero effective nonlinearity. The first phase-matched pure χ(3) THG in a noncentrosymmetric crystal is presented together with the improved Sellmeier and thermo-optic dispersion formulas.

Sellmeier equations for GaS and GaSe and their applications to the nonlinear optics in GaS x Se 1−x

The Sellmeier equations for GaS and GaSe are constructed from the nonlinear experiments thus far reported in the literature. The model calculations based on these equations were found to reproduce well the phase-matching conditions for second-harmonic generation of the Er:YSGG laser at 2.7960 μm and the CO2 laser lines at 9.5862 and 10.5910 μm achieved in the GaSxSe(1-x) crystals having different S concentrations of 0.004-0.412.