Z. J. Liu

Comparison of c-Nd:YVO4/YVO4 raman lasers and c-Nd:YVO4 self-Raman lasers

Raman lasers based on c-Nd:YVO4 crystals can generate 1178 nm Stokes line, which can be frequency-doubled to realize 589 nm sodium lasers. We make comparative experimental studies of c-Nd:YVO4/YVO4 Raman lasers and c-Nd:YVO4 self-Raman lasers. About these two kinds of lasers, the output characteristics of power, center wavelength and beam quality are measured and compared.

3D dynamic contrast-enhanced MRI of rectal carcinoma at 3T: correlation with microvascular density and vascular endothelial growth factor markers of tumor angiogenesis.

To determine how dynamic contrast‐enhanced (DCE) MRI at 3T correlates with rectal carcinoma angiogenesis.

High efficiency Nd:YAG ceramic eye-safe laser operating at 1442.8 nm

We report on a diode-pumped Nd:YAG ceramic laser operating at 1442.8 nm for the first time. In our experiment, two different Nd:YAG ceramics with the Nd-doped concentrations of 1.0 and 0.6 at. % and a Nd:YAG with the Nd-doped concentration of 1.0 at. % were used as the laser gain mediums, respectively. At a pump power of 20.7 W, a maximum output power of up to 3.96 W with optical-to-optical efficiency of up to 19.1% was obtained by using the 1.0 at. % Nd-doped ceramic as the laser gain medium. To the best of our knowledge, this is the highest output power of a LD-pumped 1.44 μm Nd:YAG ceramic laser and the highest optical-to-optical efficiency of a LD-pumped 1.44 μm Nd-doped crystal laser.

LD side-pumped Nd:GGG CW laser operating at 1110 and 1105 nm dual wavelengths and 1110 nm single wavelength

A diode-side-pumped continuous-wave Nd:GGG laser operating at dual-wavelength (1110 and 1105 nm) and single wavelength of 1110 nm is demonstrated for the first time. The maximum output power of the 1110 and 1105 nm dual-wavelength operation is 13.2 W. By adjusting the orientation of an insertion mirror, the relative intensities of the two wavelengths can be changed. Thus single wavelength operation at 1110 nm is obtained, and the output power is 9.6 W.

Experiments with an intracavity BaTeMo2O9 Raman laser

A diode-side-pumped actively Q-switched intracavity Raman laser emitting at 1178 nm employing Nd:YAG as the gain medium and BaTeMo2O9 as the Raman medium is realized. With a pump power of 115 W and pulse repetition rate of 10 kHz, a maximum first-Stokes output power of 1.9 W is obtained. The corresponding diode-to-first-Stokes conversion efficiency is 1.7% and the first-Stokes pulse width is 35 ns. The preliminary experiments proved that an intracavity BaTeMo2O9 Raman laser is feasible.

Properties of continuous-wave 1123 nm laser with diode-side-pumped Nd:YAG

Laser properties of diode-side-pumped Nd:YAG laser operating at 1123 nm are demonstrated. A 1.0 at % Nd-doped Nd:YAG rod with a size of Ø3 × 63 mm2 is used as the active medium. Both radial and tangential thermal focal lengths of this side-pumped Nd:YAG rod are determined under lasing condition. The results show that the bifocusing strength of 1123 nm laser is larger than that of 1164 nm laser, and 1123-nm thermal focal lengths are shorter than those of 1064-nm laser due to higher quantum defect. Laser output performances of 1123 nm in terms of stability, output power and beam quality influenced by pump power at different cavity lengths are also discussed with a convex-piano cavity.

A diode pumped passively mode-locked Nd:CaGdAlO4laser

A diode pumped passively mode-locked Nd:CaGdAlO4 (Nd:CGA) laser was demonstrated. By using a semiconductor saturable-absorber mirror (SESAM) as the modulator, stable mode-locked pulses with a duration of 6.0 ps and a repetition rate of 88.3 MHz have been achieved at a central wavelength of 1078.6 nm. The maximum output power of 452 mW was obtained under a pump power of 10 W.

A frequency-doubled Nd:YAG/KTP laser at 561 nm with diode side-pumping

An intracavity KTiOPO4 (KTP) frequency doubling laser emitting at 561?nm is achieved within a diode side-pumped acousto-optically Q-switched Nd:YAG laser. A compact convex?flat straight cavity is employed to achieve the compact configuration, where coatings are specially designed to suppress unwanted lines. At the pump power of 147?W and the pulse repetition rate of 10?kHz, the output power of 8.1 W was obtained at 561?nm. The corresponding optical-to-optical conversion efficiency is 5.5%. The pulse width of a 561?nm wave is 210?ns. The M2 factors are measured to be 15.5 and 17.5 in the horizontal and vertical directions respectively.

Eye-safe Raman laser at 1532 nm with BaWO4 crystal

A diode-end-pumped actively Q-switched eye-safe intracavity Raman laser at 1532 nm is demonstrated, with Nd:YVO4 as the laser crystal and BaWO4 as the Raman crystal. The highest average power of 1.5 W is obtained, with an incident pump of 12 W and a pulse repetition rate of 35 kHz, corresponding to a diode-to-Stokes conversion efficiency of 12.5%.

High-efficiency diode-pumped actively Q-switched ceramic Nd:YAG/BaWO 4 Raman laser operating at 1666 nm

A diode-pumped actively Q-switched Raman laser employing BaWO4 as the Raman active medium and a ceramic Nd:YAG laser operating at 1444 nm as the pump source is demonstrated. The first-Stokes-Raman generation at 1666 nm is achieved. With a pump power of 20.3 W and pulse repetition frequency rate of 5 kHz, a maximum output power of 1.21 W is obtained, which is the highest output power for a 1.6 μm Raman laser. The corresponding optical-to-optical conversion efficiency is 6%; the pulse energy and peak power are 242 μJ and 8.96 kW, respectively.