Composite Yb : YAG/Cr4+: YAG ceramics picosecond microchip lasers

Efficient laser-diode pumped picosecond self-Q-switched all-ceramic composite Yb: YAG/ Cr4+: YAG microchip lasers with 0.72 MW peak power has been developed. Lasers with nearly diffraction-limited beam quality (M-2 < 1.09), oscillate at stable single- and multi- longitudinal-modes due to the combined etalon effects in the Yb:YAG and Cr4(+:) YAG parts of its binary structure. (C) 2007 Optical Society of America

Positive hysteresis of Ce-doped GAGG scintillator

Pr 3+ Scintillator a b s t r a c t Positive hysteresis and radiation tolerance to high-dose radiation exposure were investigated for Ce 1% and 3% doped Gd 3 (Al, Ga) 5 O 12 (Ce:GAGG) crystal scintillator on comparison with other garnet scintillators such Ce:YAG, Ce:LuAG, Pr:LuAG, and ceramic Ce:GAGG. When they were irradiated by several Gy 60 Co c-rays, Ce 1% doped GAGG crystal exhibited $20% light yield enhancement (positive hysteresis). This is the first time to observe positive hysteresis in Ce doped GAGG. On the other hand, other garnet materials did not show the positive hysteresis and their light yields were stable after 800 Gy irradiation except Pr:LuAG. The light yield of Pr:LuAG decreased largely. When irradiated Ce:GAGG which showed positive hysteresis was evaluated in Synchrotron facility (UVSOR), new excitation band was created around 60 nm

Near-diffraction-limited passively Q-switched Yb : Y3Al5O12 ceramic lasers with peak power > 150 kW

Laser-diode pumped nearly diffraction-limited beam quality (M-2 < 1.05), high peak power, subnanosecond passively Q-switched Yb:Y3Al5O12 ceramic miniature laser with Cr4+:Y3Al5O12 ceramic as saturable absorber has been achieved. The slope efficiency is as high as 36% for 80% initial transmission of Cr4+:Y3Al5O12 ceramic. The pulse width of 335 ps and peak power of over 150 kW at repetition rate of 5 kHz were obtained. Laser oscillates at single-longitudinal-mode oscillation and wide-separated multilongitudinal-mode oscillation due to the combined etalon effect of the Cr4+:YAG thin plate and thin glass plate as output coupler. (c) 2007 American Institute of Physics

Laser-diode pumped heavy-doped Yb : YAG ceramic lasers

Laser performance of heavy-doped Yb:YAG ceramics was investigated using a two-pass pumping miniature laser configuration. Slope efficiency of 52% and optical-to-optical efficiency of 48% have been achieved for 1-mm-thick YAG ceramic doped with 20 at. % ytterbium ions. Laser spectra of Yb:YAG ceramic and single-crystal lasers were addressed under different intracavity laser intensities. Heavy-doped Yb:YAG ceramic is more suitable for a thin disk laser than a single-crystal with the same Yb3+-ion lasants. (c) 2007 Optical Society of America

Ytterbium and chromium doped composite Y3Al5O12 ceramics self-Q-switched laser

Composite Yb:Y3Al5O12/Cr:Y3Al5O12 ceramics were fabricated by using vacuum sintering technique and nanocrystalline technology. Self-Q-switched composite Yb:Y3Al5O12/Cr:Y3Al5O12 ceramic lasers with pulse energy of 125 mu J and peak power of over 105 kW at repetition rate of 3.8 kHz have been demonstrated. Nearly diffraction-limited beam quality with M-2 less than 1.35 was achieved in this composite Yb:Y3Al5O12/Cr:Y3Al5O12 ceramic self-Q-switched lasers. (C) 2007 American Institute of Physics

The temperature dependence of gamma-ray responses of YAG:Ce ceramic scintillators

The temperature dependence (from -20 to +20 degrees C) of gamma-ray irradiated light outputs, energy resolutions, and decay time profiles of three YAG:Ce poly-ceramic scintillators are studied. The Ce concentrations are 0.5, 0.05, and 0.005 mol%.0 The relative light yield of the YAG:Ce with 0.5 mol% with a 2 μs shaping time was measured as 1 : 1.08 : 1.14 at +20, 0, and -20 degrees C, respectively, including the temperature dependence of the phototube (-0.2% /degree). The energy resolution stays almost constant at 7.2-1.984238or 662 keV gamma-rays. The ceramic with 0.05 mol??к_?ۿ?Sڟ?hows the almost same properties, while the light yield of that with 0.005 mol-1230736516s 2-4 times lower (hence the energy resolution becomes 14-19%). All the scintillators exhibit good linearities within ∼ 1 % between the light output and the irradiated gamma-ray energy from 59.5 keV to 662 keV. The decay time constants of the dominant decay components are about 80 ns and 300 ns at +20 degrees C. As the temperature increases from -20 to +20 degrees C, the effective decay of all the ceramics becomes faster, because the decay time constants and fractions of the slower components shorten and decrease, respectively. This result suggests that carriers which are captured in shallow traps before transferring excitation to Ce ions can escape the traps more easily at higher temperatures. Considering the decrease of the total light yield toward higher temperatures, it is thought that thermal quenching starts to dominate the temperature dependence of the ceramic YAG:Ce around the room temperature. The 0.5 mol?ڿ?R?@ʿ???S?cintillator shows a lower quenching energy than the 0.05 mol1001122502ne. This can be explained in terms of self absorption of Ce emission

Efficient Yb3+: Y3Al5O12 ceramic microchip lasers

Low-threshold and highly efficient continuous-wave (cw) Yb3+:Y3Al5O12 (Yb:YAG) ceramic laser with near-diffraction-limited beam quality was demonstrated at room temperature. Dual-wavelength operation at 1030 and 1049 nm with 5% transmission of the output coupler was achieved by varying pump power intensity. Slope efficiencies of 79% at 1030 nm and 67% at 1049 nm were achieved for 1-mm-thick Yb:YAG ceramic plate (C-Yb=9.8 at. %) under cw laser-diode pumping. The effect of pump power on the laser emission spectra of both wavelengths is addressed. Excellent laser performance indicates that Yb:YAG ceramic laser materials could be potentially used in high-power solid-state lasers. (c) 2006 American Institute of Physics