Enhanced mid-infrared emission of Pr ions in solids through a "3-for-1" excitation process - quantified.

Evidence is presented that a "three-for-one" process based on two cross-relaxations between Pr ions efficiently populates the mid-infrared-emitting H manifold in a Pr-doped low-maximum-phonon-energy host. The concentration dependence of infrared fluorescence spectra and lifetimes of polycrystalline Pr:KPbCl initially excited to the F manifolds indicate that the 3500-5500-nm fluorescence becomes strongly favored over shorter-wavelength infrared emission bands in the higher-concentration sample. The strong concentration dependence of the F and H manifold lifetimes suggests that both of these decay by cross-relaxation processes, resulting in more than one ion excited to H for each ion initially excited to F.

Pr:RbPbCl: temperature dependent spectra, dynamics and three-for-one excitation: erratum.

We present an erratum regarding the contents of Table 1.

Pr:RbPbCl: temperature dependent spectra, dynamics and three-for-one excitation.

The temperature dependence of the absorption, fluorescence, and fluorescence lifetimes of states relevant to short-wave-infrared and mid-infrared laser operation have been measured in Pr:RbPbCl. The 3600-5500-nm fluorescence grows strongly with temperature, and at room temperature represents the large majority of the observed photon flux. Intra-ionic decay processes cannot explain this dominance, but a combination of two cross-relaxation processes provides good agreement with the data.

Co-precipitation of rare-earth-doped YO and MgO nanocomposites for mid-infrared solid-state lasers.

Mid-infrared, solid-state laser materials face three main challenges: (1) need to dissipate heat generated in lasing; (2) luminescence quenching by multiphonon relaxation; and (3) trade-off in high thermal conductivity and small maximum phonon energy. We are tackling these challenges by synthesizing a ceramic nanocomposite in which multiple phases will be incorporated into the same structure. The undoped majority species, MgO, will be the main carrier of high thermal conductivity, and the minority species, Er:YO, will have low maximum phonon energy.

Resonantly diode-pumped Ho3+:Y2O3 ceramic 2.1 µm laser.

We report what is believed to be the first laser operation based on Ho3+-doped Y2O3. The Ho3+:Y2O3 ceramic was resonantly diode-pumped at ~1.93 µm to produce up to 2.

Efficient resonantly pumped tape cast composite ceramic Er:YAG laser at 1645 nm.

Laser operation of a composite ceramic Er:YAG rod is demonstrated at 1645 nm with a slope efficiency of 56.9% under resonant pumping at 1532.3 nm.

Temperature dependence of a diode-pumped cryogenic Er:YAG laser.

We report the laser performance of resonantly diode-pumped Er:YAG from liquid nitrogen temperature to above room temperature. Relative to incident pump power, the best performance was observed at approximately 160 K. Spectroscopy and modeling show that this is due primarily to the changing efficiency of diode pump absorption as the absorption lines broaden with temperature.

Ultralow quantum-defect eye-safe Er:Sc2O3 laser.

Resonantly pumped Er(3+):Sc(2)O(3) laser operation is achieved with a quantum defect (QD) of 1.5% at liquid nitrogen temperature. The laser, in-line pumped at 1535 nm, operated at 1558 nm with a slope efficiency of over 45%.

Concentration quenching in fine-grained ceramic Nd:YAG.

We have studied the concentration dependent fluorescence decay kinetics of ceramic Nd:YAG, to resolve inconsistencies in the previous literature. Our data indicate that earlier reports of single exponential lifetimes even at Nd concentrations of a few percent were due to the effects of long-pulse excitation. Under short-pulse excitation the fluorescence decay is nonexponential for concentrations greater than about 1% atomic.

Ultrahigh-gain bulk solid-state stimulated Brillouin scattering phase-conjugation material.

We report what is believed to be the first observation of phase conjugation by stimulated Brillouin scattering (SBS) in TeO2 single crystal. The observed very low threshold for phase-conjugate mirror (PCM) formation, high PCM reflectivities in this initial experiment, and commercial availability of material hold promise for a host of practical applications in the near future. The resultant steady-state gain parameter, approximately 100 cm/GW, is to our knowledge the largest ever reported for any SBS material.

Multiple pulse laser-induced damage phenomena in silicates.

Multiple pulse laser-induced bulk damage has been studied in fused silica and borosilicate glass. The fluence dependence and pulse repetition frequency dependence of the damage make it clear that laser irradiation promotes damage on subsequent pulses, and the evidence favors attribution of the effect to transient entities such as point defects rather than larger imperfections such as inclusions. However, the influence of preirradiation defects on damage thresholds is small, and a luminescence experiment places low limits on the possible concentration of conduction band electrons prior to damage.