Guenter Huber

Green upconversion continuous wave Er3+:LiYF4 laser at room temperature

We report room‐temperature upconversion pumped continuous wave laser emission of 1% Er3+:LiYF4 at 551 nm excited by a Ti:sapphire laser at 810 nm. Output powers of up to 40 mW with output coupling of 6.6% have been obtained by using nearly concentric resonator design.

cw double cross pumping of the 5I7–5I8 laser transition in Ho3+‐doped garnets

We obtained for the first time efficient room‐temperature cw lasing at 2.086 μm in Cr,Tm,Ho:YScAl‐garnet and Cr,Tm,Ho:YScGa‐garnet crystals. Double cross pumping via Cr3+ and Tm3+ with a krypton pump laser yields threshold pump powers of 25 mW and slope efficiencies up to 13%. Broad band pumping can also be expected.

Optical properties of Nd 3+ - and Tb 3+ -doped KPb 2 Br 5 and RbPb 2 Br 5 with low nonradiative decay

We report on the optical properties of Nd3+- and Tb3+-doped low-phonon-energy moisture-resistant host crystals, potassium lead bromide (KPb2Br5), and rubidium lead bromide (RbPb2Br5), including absorption, emission, and emission lifetime measurements as well as calculations of the multiphonon decay rate, Judd–Ofelt parameters, and radiative transition probabilities for relevant (laser) transitions in these crystals. The RE3+:MPb2Br5 (M=Rb, K) crystal is a promising candidate for long-wavelength infrared applications because of the low phonon frequencies and other favorable features.

Orange and red upconversion laser pumped by an avalanche mechanism in Pr3+, Yb3+:BaY2F8

The letter reports on upconverted orange (607.5 nm, 3P0→3H6) and red (638.7 nm, 3P0→3F2) laser oscillation at room temperature observed in Pr3+, Yb3+:BaY2F8 under excitation at 822 or 841 nm at 300 K. The upconversion mechanism that populates the emitting level is an avalanche excitation mechanism. Output powers up to 55 mW and slope efficiencies up to 27% were demonstrated at 607.5 nm. At 638.7 nm, the maximum output power was 26 mW with a slope efficiency of about 13.5%.

Tunable room-temperature cw laser action in Cr3+: GdScAl-garnet

We report for the first time on tunable room temperature cw laser action of a transition metal laser material. In Cr3+:GdScGa-garnet crystals almost the total fluorescence is channelled into the broad band4T2→4A2 transition. The fluorescence lifetime is τ=120 μs. Laser pumping in the blue-green and yellow-red spectral range yields pump thresholds around 250 mW and slope efficiencies up to 11%. The wavelength of the free running Cr3+ laser is centered at 777 nm.

Room‐temperature green laser emission of Er:LiYF4

We report the first demonstration of a green erbium‐doped crystal laser at room temperature. Excited with a pulsed dye laser, the erbium‐doped LiYF4 crystal emitted on the 4S3/2–4I15/2 ground state transition. As expected from fluorescence measurements, the emitted radiation was polarized parallel to the optical axis. Laser oscillation has also been observed in erbium‐doped Y3Al5O12 and Lu3Al5O12 crystals.

30 Hz operation of 2μ-Ho and Tm-lasers

Abstract We investigated the behaviour of Cr,Tm-YAG and Cr,Tm,Ho-YAG laser rods at high repetition rates. For both crystals repetition rates up to 30 Hz were achieved. The maximum output power was 6.5 W for Cr,Tm,Ho-YAG and 3 W for Cr,Tm-YAG.

Switching of emissivity and photoconductivity in highly doped Yb3+:Y2O3 and Lu2O3 ceramics

Reversible jump of thermal emission accompanied with jump of photocurrent is observed in highly doped Yb3+:Y2O3 and Lu2O3 bulk ceramics pumped at 940nm wavelength. In contrast, when these materials are heated with a CO2 laser at 10.6μm wavelength, only a gradual increase of thermal emission and photoconductivity are observed up to the melting point. These results are interpreted as a ytterbium mediated, photoassisted avalanche of thermal emission.

cw laser action of Er3+ in double sensitized fluoroaluminate glass at room temperature

cw lasing at 1.6 μm was obtained for the first time in Cr, Yb, Er:fluoroaluminate glass. Double step pumping via Cr3+ and Yb3+ with a krypton laser yields a threshold pump power of 80 mW. Efficient lasing can be expected using glass samples of optimized dopant concentration and improved optical quality.

Continuous wave Praseodymium solid-state lasers

We review spectroscopic properties, basic laser parameters, and efficient lasing of Pr-doped fluoride materials. Continuous output powers up to 600 mW in the visible spectral range as well as intracavity frequency doubling to the UV spectral region under semiconductor laser pumping is reported. We achieved powers of 600 mW in the visible spectral region and 360 mW of UV radiation corresponding to a conversion efficiency of 61% with an optical-to-optical efficiency of 22%.