Huagang Liu

Phase matching analysis of noncollinear optical parametric process in nonlinear anisotropic crystals

Phase matching for noncollinear optical parametric generation is investigated. All the possible phase matching configurations and existence conditions for general noncollinear three-wave mixing interactions are derived for propagation within the crystal principal planes. Numerical expressions for the critical phase matching angles are presented wherever possible. Finally, as an application of these expressions, several numerical calculations of the phase matching angles for general noncollinear phase matched optical parametric amplification in the nonlinear-optical crystals such as beta -BaB2O4, LiB3O5 and KTiOPO4 are completed. and the results are graphically presented

Growth of YAl3(BO3)4 crystals with tungstate based flux

Abstract A new flux made of Li2WO4–B2O3 was used to grow YAl3(BO3)4 (YAB) crystals. The crystallisation region of YAB crystals was determined in the quasi-ternary system YAB–Li2WO4–B2O3. Large and transparent YAB crystals were grown by a high temperature top seeding method with Li2WO4–B2O3 as the flux. The volatility of Li2WO4–B2O3 flux was lower than that of the commonly used polymolybdate flux at high temperature. A much lower incorporation of tungstate into the crystals was observed. The ultraviolet cutoff wavelength of YAB crystal was shorter than 190 nm. The thermal expansion coefficients along two crystallographic directions over the measuring temperature range of 30–800°C were determined to be αau200a=u200a3·88×10−6 K−1 and αcu200a=u200a12·5×10−6 K−1 respectively. The specific heat is ∼0·675 J g−1 K−1 at room temperature. The thermal conductivities at room temperature are 11·891 and 11·591 W m−1 K−1 along the a and c directions respectively.

Efficient 2122 nm Ho:YAG laser intra-cavity pumped by a narrowband-diode-pumped Tm:YAG laser

We first demonstrate an efficient Ho:YAG laser intra-cavity pumped by a narrowband-diode-pumped Tm:YAG laser. The pump wavelength of the laser diode was selected according to the excitation peak which is also one of the absorption peaks of a 3.5 at. % Tm:YAG crystal and was locked by volume Bragg gratings. In the Tm laser experiment, a maximum output power of 11.12 W, corresponding to a slope efficiency of 51.6%, was obtained. In the Ho laser experiment, a maximum output power of 8.03 W at 2122 nm with a slope efficiency of 38% was obtained for 24.96 W of diode pump power incident on the Tm:YAG rod.

Two-beam combined 3.36 J, 100 Hz diode-pumped high beam quality Nd:YAG laser system

In this paper, we develop a diode-pumped all-solid-state high-energy and high beam quality Nd:YAG laser system. A master oscillator power amplifier structure is used to provide a high pulse energy laser output with a high repetition rate. In order to decrease the amplifier working current so as to reduce the impact of the thermal effect on the beam quality, a beam splitting-amplifying-combining scheme is adopted. The energy extraction efficiency of the laser system is 50.68%. We achieve 3.36 J pulse energy at a 100 Hz repetition rate with a pulse duration of 7.1 ns, a far-field beam spot 1.71 times the diffraction limit, and 1.07% energy stability (RMS).

Generation of 3.8-GHz Picosecond Pulses From a Diode-Pumped Self-Mode-Locked Yb:YAG Thin Disk Laser

We report on a high-repetition-rate self-mode-locking laser with a diode-pumped Yb:YAG ceramic thin disk. The third nonlinearity of the gain medium is exploited to achieve stable CW mode-locking operation without using any additional components in the cavity. The laser produces 60-ps pulses at the central wavelength of 1032 nm with a repetition rate of 3.8 GHz and an average power of 780 mW.

High-repetition-rate single-frequency electro-optic Q-switched Nd:YAG laser with feedback controlled prelase

A stable high-repetition-rate, high pulse energy and single-frequency electro-optic Q-switched laser has been developed and demonstrated in this paper. The prelase technique has been used in this single-frequency laser. And a PID feedback control electronics is applied to stabilize the prelase. Meanwhile, a two-plate resonant reflector take the place of traditional dielectric output coupler mirror to enhance the single-axial-mode selection. And a Cr:YAG saturable absorber is also inserted in the cavity to improve single-axial-mode selection. Output laser power over 2 W with 10 ns pulse duration has been obtained at a repetition rate of 1 kHz. And the single-axial-mode probability was 100% in one hour without any manual adjustments. The experimental results show that the prelase technique is reliable to attain single-frequency operation.