Chaoyang Tu

Comparison of optical spectra of Nd3+ in NdAl3(BO3)4 (NAB), Nd:GdAl3(BO3)4 (NGAB) and Nd:Gd0.2Y0.8Al3(BO3)4 (NGYAB) crystals

A comparative study of the optical absorption and luminescence of crystals of NdAl3(BO3)4 (NAB), Nd:GdAl3(BO3)4 (NGAB) and Nd:Gd0.2Y0.8Al3(BO3)4 (NGYAB) is presented. The Judd-Ofelt theory is applied to the fitting of experimental absorption line strengths to obtain the intensity parameters Ωt (t = 2,4,6) with root mean square errors of 11.8%, 3.8% and 8.6% for NAB, NGAB and NGYAB respectively. The intensity parameters are used to calculate the radiative transition rates, branching ratios and radiative lifetimes of Nd3+ ions undergoing transitions from 4F3/2 to 4IJ manifolds. The relevant spectroscopic parameters for laser applications (quantum efficiency and emission cross section) are also estimated. The results are compared among the three samples and other borate crystals. It is concluded that NAB is a laser crystal with high gain and thus a promising candidate for microchip laser application, while NGAB (or NGYAB) can be used as an alternative to the celebrated nonlinear laser crystal NYAB.

Raman lasers at 1.171 and 1.517 μm with self-frequency conversion in SrWO4:Nd3+ crystal

We have grown and characterized a SrWO4:Nd3+ crystal. Photoluminescence and Raman spectra are exhibited. We have obtained end-pumped self-stimulated Raman scattering in the two and laser channels leading to 1.171 and 1.517xa0µm coherent radiations. The latter is close to the eye-safe range of wavelengths.

Highly efficient diode-pumped actively Q-switched Nd:YAG-SrWO(4) intracavity Raman laser.

A highly efficient diode-pumped actively Q-switched intracavity Raman laser with SrWO(4) as the Raman-active medium is presented. As high as 23.8% diode-to-Stokes optical conversion efficiency is obtained with an incident pump power of 7.17 W and a pulse repetition rate of 15 kHz.

Spectra and intensity parameters of Li6Y (BO3)3:Nd3+ laser crystal

Abstract The absorption line strengths were measured for Nd 3+ ions in Li 6 Y(BO 3 ) 3 . Using these data, intensity parameters Ω λ (λ=2, 4, 6), radiative transition probabilities, radiative lifetime, fluorescence branching ratios, quantum efficiency and stimulated emission cross sections were calculated by the Judd-Ofelt theory and related to the laser action of this crystal.

Self-sum- and -difference-frequency mixing in GdAl(3)(BO(3))(4):Nd(3+) for generation of tunable ultraviolet and infrared radiation.

We exploited Nd(3+) laser emission at 1061.9 nm ((4)F(3/2)?(4)I(11/2) channel) in a self-chi((2)) active GdAl(3)(BO(3))(4):Nd(3+) laser crystal. UV radiation was obtained from a 1.8% yield from self-sum-frequency mixing: 1/pump + 1/1061.9 = 1/UV, during pumping in the Nd(3+) (4)G(5/2)-(2)G(7/2) levels near 588 nm. The UV tunability had a range of 378-382 nm. We have demonstrated, for the first time to our knowledge, generation of coherent IR radiation from a self-difference-frequency mixing laser: 1/pump - 1/1061.9 = 1/IR. We got a 0.5% yield and tunability in the 1305-1365-nm range.

Spectroscopy, laser operation at 1.3 μm and self-frequency doubling in GdAl3(BO3)4: Nd3+

Abstract We report for the first time the spectroscopy and the laser operation of GdAl 3 (BO 3 ) 4 : Nd 3+ (NGAB) near 1338 nm corresponding to the 4 F 3/2 → 4 I 13/2 channel. Their features have been found favorable for self-frequency doubling in order to generate a red radiation at 669 nm and more generally for self-frequency conversions. The emission cross-section in σ-polarization was estimated to be 5.5×10 −20 cm 2 . We demonstrated self-frequency doubling despite of non-optimal experimental conditions.

Crystal growth of KGd (WO4)2:Tm3+

Abstract The Tm 3+ :KGd (WO 4 ) 2 crystal with the size up to 50xa0mm was grown from the K 2 O–WO 3 –BO 3 solvent system by using the top seeded solution growth method. The absorption spectrum was measured and its absorption peaks were confirmed. The emission spectra of the crystal at 455 and 665xa0nm were obtained when a light of 360xa0nm excited this crystal. A broad emission spectrum from 1650 to 2000xa0nm was obtained when a light of 800xa0nm excited this crystal. It is expected that this crystal may be useful as a tunable infrared laser crystal.

Eye-safe laser radiation from stimulated Raman scattering frequency self-conversion in KGd(WO4)2:Nd3+

Under short-pulsed longitudinal pumping at 600 nm we obtained intracavity stimulated Raman scattering frequency self-conversion of the 1352.5 nm laser line in KGd(WO4)2:Nd3+. The wavelength which was produced is eye-safe at 1539.5 nm and the conversion efficiency was 1.26% with uncoated faces of the 3 cm long crystal.

Single-frequency crystalline Raman amplifier at 1178 nm

Single-frequency crystalline Raman amplifier at 1178 nm was demonstrated. After three stages of amplifications, the output pulse energy was 26.7 mJ and the pulse width was 2.9 ns. The linewidth was less than 500 MHz.

Optical spectroscopy of Nd3+ ions in GdXY1−XAl3(BO3)4

In this work, the optical spectroscopy (absorption and luminescence) of a new Nd 3+ activated non-linear crystal, Gd X Y 1-X Al 3 (BO 3 ) 4 , with x=0.25, has been investigated. The crystal structure of this system is quite similar to that of one of the best self frequency doubling crystals, YAl 3 (BO 3 ) 4 (YAB). Results show absorption bands very similar, but broader than those observed in Nd:YAB. This suggests the possibility of two non-equivalent environments for the Nd 3+ ions, corresponding to the replacement of Y 3+ and Gd 3+ lattice sites.