Compact deep ultraviolet frequency-doubled Tb:LiYF4 lasers at 272 nm.

A new laser system has been developed to generate coherent deep ultraviolet (DUV) radiation at 272 nm. The DUV lasers were produced via intra-cavity frequency doubling of the Tb3+:LiYF4 lasers emitting fundamentally at 544 nm. Continuous-wave (cw) and Q-switched operations were performed with a type I phase-matched ß-BaB2O4 nonlinear crystal. The cw operation produces 127 mW of averaged DUV output power. Passive Q-switched operation was realized by using Co2+:MgAl2O4 saturable absorbers. At an initial transmittance (excluding Fresnel reflections) of 99% at 544 nm, stable pulsed output at 272 nm with maximum single-pulse energy of 7.6 µJ and peak power of 6.1 W was obtained. Furthermore, by employing a smaller initial transmittance of 94.7%, we achieved maximum averaged DUV output power of 277 mW. The statistically averaged single-pulse DUV energy and peak power were estimated to be around 100 µJ and 320 W, respectively, which indicates great potential for this DUV laser system toward high energy and peak power.

Highly efficient Er:YAP laser with 6.9 W of output power at 2920†nm.

We report on the efficient high-power operation of a laser-diode-pumped Er3+-doped yttrium aluminum perovskite (Er:YAP) laser in the 3 µm spectral region at room temperature. 6.9 W of continuous-wave (CW) output power was obtained at 2920 nm. The slope efficiency was as high as 30.6% with respect to the absorbed pump power, which is close to the quantum defect limit (33.4%). To the best of our knowledge, this is the highest CW output power generated from 3 µm Er3+-doped solid state lasers at room temperature. Furthermore, our analysis has shown that more than 10 W of output power based on Er:YAP is possible by further mitigating the thermal lens effect.

Verdet constant of potassium terbium fluoride crystal as a function of wavelength and temperature.

Potassium terbium fluoride KTb3F10 (KTF) crystal is a promising magneto-active material for creating multi-kilowatt average-power Faraday isolators operating at the visible and near-infrared wavelengths. Nevertheless, the key material's parameter needed for the design of any Faraday isolator-the Verdet constant, has not been comprehensively investigated yet. In this Letter, we report on measurement of the Verdet constant of the KTF crystal for wavelengths between 600 and 1500 nm and for temperatures ranging from 15 to 295 K. A suitable model for the Verdet constant as a function of wavelength and temperature has been developed and may be conveniently used for optimal design of KTF-based high-average-power Faraday isolators.

Efficient Pr:YAlO3 lasers at 622†nm, 662†nm, and 747†nm pumped by semiconductor laser at 488†nm.

We report laser operation of Pr:YAlO3 pumped by a frequency-doubled optically pumped semiconductor laser. Continuous-wave laser oscillations at around 622 nm, 662 nm, and 747 nm were demonstrated in plano-concave or/and plano-plano cavities. The maximum slope efficiencies were found to be 37%, 35%, and 59%, respectively, which are record-high values for Pr:YAlO3 lasers. Furthermore, lasing at 622 nm was demonstrated at room temperature for the first time to the best of our knowledge.

Photo- and thermo-activated electron transfer system based on a luminescent europium organic framework with spectral response from UV to visible range.

A dual stimuli-responsive system was constructed by introducing methyl viologen into a luminescent europium-organic framework with a compact packing mode. In addition to absorption and emission properties that are sensitive to both light and heat involving electron/energy transfer processes, the photoactive MOF has a spectral response from UV to the visible region.

Photo- and thermally induced coloration of a crystalline MOF accompanying electron transfer and long-lived charge separation in a stable host-guest system.

A new type of electron transfer (ET) system was built via the combination of a highly stable MOF host framework and methyl viologen guest molecule. The π-stacking arrangements adjust the distance between the D-A components, contributing to the formation of an ultra long-lived charge separated state in the photo/thermo dual stimuli-responsive complex.