RESUMEN
The first observations, to the authors' knowledge, of transient thermal lensing in a ZnGeP(2) crystal achieved with 2.09-µm laser excitation of 800-µs, 70-mJ pulses at 30 Hz and by burst-mode Q-switched pumping are presented. The laser power transmitted through an aperture was approximated by an adiabatic model with currently accepted values for the thermal properties of ZnGeP(2) and corresponded to focal-length changes from infinity to 10 cm during each 800-µs pulse. Similar results were seen when the crystal was operated as an optical parametric oscillator. This transient thermal lens severely limits ZnGeP(2) as a material for use in optical parametric oscillators for these modulated, high-power operating conditions.
RESUMEN
We performed an experimental investigation of thermal lensing in silver gallium selenide (AgGaSe(2)) optical parametric oscillator crystals pumped by a 2-µm laser at ambient temperature. We determined an empirical expression for the effective thermal focusing power in terms of the pump power, beam diameter, crystal length, and absorption coefficient. This relation may be used to estimate average power limitations in designing AgGaSe(2) optical parametric oscillators. We also demonstrated an 18% slope efficiency from a 2-µm pumped AgGaSe(2) optical parametric oscillator operated at 77 K, at which temperature thermal lensing is substantially reduced because of an increase in the thermal conductivity and a decrease in the thermal index gradient dn/dT. Cryogenic cooling may provide an additional option for scaling up the average power capability of a 2-µm pumped AgGaSe(2) optical parametric oscillator.
RESUMEN
We report new experimental results on the spectral, thermal, and orientational characteristics of stoichiometry-dependent mid-IR absorption in AgGaSe(2) crystals. In currently available material, this absorption poses an obstacle to the power scaling of the 2-µm-pumped AgGaSe(2) optical parametric oscillator (OPO). Preliminary experiments have indicated that this absorption could be substantially reduced by optimization of the process parameters during crystal growth and annealing. OPO output powers approaching 10 W may be achievable by using optimized material.
RESUMEN
We report what is to our knowledge the first room-temperature operation of an efficient flash-lamp-pumped Cr,Tm:YAG laser at 2.014 microm. Thresholds as low as 43 J, output energies exceeding 2 J, and slope efficiencies as high as 4.5% have been achieved using a compact diffuse-reflecting pump cavity. These efficiencies are an order of magnitude higher than those previously reported for a 2.01-microm Cr,Tm:YAG laser operated at cryogenic temperatures.
RESUMEN
An oscillator-amplifier system has been constructed using (F(2)(+))(A) centers in KCl:Li crystals and a 1.41-microm laser pump generated by Raman shifting a 1.06-microm Nd:YAG line in liquid nitrogen. Output energies of 2.3 mJ and peak powers exceeding 0.4 MW were achieved. The system was tuned continuously over the 2.0-2.4-microm spectral wavelength range.
RESUMEN
Laser action has been achieved by using lithium (F(2)(+))(A) centers in KI. The laser is continuously tunable from 2.59 to 3.65 microm; the 1.73-microm line from a pulsed Er:YLF laser is used as pump source.
RESUMEN
Continuous-wave, broadly tunable laser action is reported for an (F2+)A center in lithium-doped KC1. The laser is continuously tunable from about 2.00 to 2.50 microm, is highly efficient, has a low threshold for absorbed power, and retains its laser capability after several weeks of storage at room temperature.
