A high-average-power, high-repetition-rate dual signal optical parametric oscillator based on periodically poled MgO-doped lithium niobate (PPMgLN) with a phase-reversed grating is reported. The pump laser is an acousto-optically Q-switched Nd:YVO4 laser with a maximum average power of 7.6 W. When the repetition rate is 50 kHz and the pulse width of the pump source is 23 ns, the maximum average dual signal output power is about 1.9 W, leading to a conversion efficiency of 25%. Over a 30-min interval, the instability of the signal power measured is less than 0.5%.

利用声光调Q Nd:YVO4激光器输出的1064 nm激光抽运周期极化掺氧化镁LiNbO3(PPMgLN)晶体,实现了角度调谐的双信号光运转准相位匹配(QPM)光参量输出。PPMgLN晶体长50 mm,具有周期相位反转结构,极化周期29.6 μm,相位反转周期6.808 mm,利用外加电场极化法制作,极化沿晶体的z向进行。在晶体外部旋转角度为0°-8°范围内,实现了双信号光波在1474.8-1479 nm和1489.5-1495.2 nm波段的快速调谐输出。对角度调谐准相位匹配进行了相应的理论分析,理论结果与实验值较为一致。

We report a tunable quasi-phase-matched optical parametric generator (OPG) with different wedge angles, pumped by a commercially available Q-switched diode-pumped Nd:YVO4 laser with a repetition of 50 kHz. The nonlinear crystal is a periodically poled MgO-doped LiNbO3 (PPMgOLN) with a period of 30 um. A congruent bulk LiNbO3 (LN) with three different wedge angles of 0, 4, and 9 deg. is placed in front of PPMgOLN. Rapid tuning has been achieved by simply moving the LN crystal along its lateral direction and over 60-mW average signal output power was obtained in the whole wavelength tuning range of 1539-1570 nm.

The influence of the KTiOPO4 (KTP) crystal boundary temperature on conversion efficiency in high power green laser has been studied theoretically and experimentally. Temperature distribution inside the KTP crystal has been analyzed by solving the thermal conductivity equation. From the temperature distribution inside the KTP crystal, we have calculated the optimal phase-matching angles of the type-II KTP crystal as a function of temperature. The second-harmonic conversion efficiency as a function of temperature has also been calculated. In the experiment, two KTP crystals with different phase-matching angles were used in the intrcavity-frequency-doubled resonator. When the boundary temperature of KTP-A (φ = 23.6o, θ = 90o under the condition of 27 oC temperature) was setting at 4 oC, a maximum green light power of 104 W was generated at repetition rate of 20.7 kHz and pulse width of 132 nm with pumping current of laser diode of 18.3 A, leading to 10.2% optical-to-optical conversion efficiency. When KTP-B crystal (φ = 24.68o, θ = 90o under the condition of 80 oC temperature) was employed, an average output power of 110 W at 532 nm has been achieved with values of 11.5% and 2% for the optical-to-optical efficiency and the instability, respectively. The optimal boundary temperature of this KTP crystal has been found to be 48.8 oC.

报道了一台高功率内腔倍频全固态Nd∶YAG绿光激光器，针对KTP晶体热效应和激光热稳定腔，采取了对KTP晶体进行低温冷却的优化措施，以便减少KTP晶体的热效应导致的相位失配，同时兼顾了Nd∶YAG棒的热致双折射效应和KTP晶体热透镜效应，设计了热稳定谐振腔；实验中采用80个20 W激光二极管阵列侧面抽运Nd∶YAG棒和Ⅱ类相位匹配KTP晶体(在27 ℃时相位匹配角为=23.6°；θ=90°，尺寸为7 mm×7 mm×10 mm)内腔倍频技术，谐振腔腔长为530 mm，KTP晶体的冷却温度为4.3 ℃，抽运电流为18.3 A时，实现平均功率达104 W、脉冲宽度为130 ns的532 nm激光输出；其重复频率为20.7 kHz。光光转换效率为10.2%。

The distribution of pump light and signal light in Yb^(3+)-doped double-cladding fiber laser is analyzed based on a rate equation model. Numerical simulation results are obtained. The numerical solution of the rate equation is shown to be in excellent agreement with the experimental data.

An optical parametric oscillator (OPO) based on periodically-poled lithium niobate (PPLN) and pumped by 1064.2-nm laser is demonstrated, which can be conveniently tuned by the means of changing its operating temperature. The parameters of the set-up and experimental results are introduced in this paper. We adjusted the operating temperature from 80 to 250 ℃, the output wavelength shifted from 1485.4 to 1540.7 nm. The average of the shifts is 0.33 nm/℃.

We demonstrate an angle-tuned signal-resonated optical parametric oscillator (OPO) with periodically poled lithium niobate (PPLN) pumped by a diode-pumped Nd: YVO4 laser. 1499.8 - 1506.6 nm of signal wavelength is achieved at 140℃ by rotating a 29-μm period PPLN from 0°- 10.22°in the x-y plane while keeping the pump wave vertical to the resonator mirrors. Two pairs of the signal and idler waves of the same wavelengths can be achieved symmetrically for each pair of angles of rotation with same absolute value and opposite sign. Theoretical analyses on angle-tuned PPLN-OPO with pump wave vertical to the resonator mirrors are presented and in good agreement with our experimental results. It is also found that all interacting waves in the cavity (not inside the crystal) are always collinear for PPLN-OPO with the pump wave vertical to the resonator mirrors while phase-matching is noncollinear within the crystal.

A quasi-continuous-wave intracavity frequency-doubled Nd:YAG laser which operates at 660 nm is studied. By using a flat-flat laser cavity, 2 Kr-lamps, KTP crystal and an acousto-optically Q-switch, 2-W output power at 660 nm is obtained. The relationship between laser cavity length and output power is analyzed.