We present three different dual-wavelength laser architectures to obtain cw blue radiations. They are based on diode-pumped Nd-doped crystals lasing on the 4F3/2-4I11/2 and 4F3/2-4I9/2 transitions. Blue radiations were achieved by intracavity sum frequency operation in a BiB3O6 crystal. We report a maximum output blue power of 303 mW at 491 nm for a pump power of 10 W.

A Raman scattering system devoted to high temperatures is presented. It is based on a pulsed system to remove thermal emission with retaining charge-coupled device (CCD) detection. Two types of optical gating are used: a Pockels switch or an intensified CCD (ICCD), combining in this case the optical gate and the CCD detection. The performances of both systems are presented and their respective advantages are discussed and compared. The ICCD device allows recording of spectra in the 2000 • C range, and typical results obtained on alumina and zirconia ceramics are shown.

We present what we believe to be the first true three-level laser based on a Nd-doped crystal. From the 4F3/24I9/2 laser transition, the lower laser level being the ground state, emission at 879 nm in NdGdVO4 has been obtained with diode pumping. Up to 0.8 W of power has been achieved in cw operation and 24 microJ per pulse (35 ns) in the Q-switched regime. Intracavity second-harmonic generation in the pulsed regime is also demonstrated with 17 8 mW of average output power at 439.5 nm, corresponding to an energy of 17microJ per pulse.

We present a thermal conductivity measurement method for laser crystals based on thermal mapping of the crystal face by an infrared camera. Those measurements are performed under end-pumping of the laser crystal and during laser operation. The calculation of the fraction of pump power converted into heat is therefore simplified, and it is possible to link easily the temperature in the crystal to the thermal conductivity. We demonstrate the efficiency of this measurement method with a Nd:YAG crystal, before using it to compare Nd:YVO(4) and Nd:GdVO(4) crystals.

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