温度调谐MgO：LiNbO3晶体光参量振荡器

采用调Q Nd:YAG激光倍频光(0.532μm)泵浦温度调谐MgO:LiNbO_3晶体单、双谐振光参量振荡器(OPO包括DRO、SRO)的实验结果.双谐振(DRO)调谐范围达844.1～1411.3nm,最低泵浦阈值0.22mJ/pulse;单谐振(SRO)调谐范围达738.9～1032.2nm,最低泵浦阈值0.66mJ/pulse.最大能量转换效率为10.4%.     

宽波段温度调谐MgO∶LiNbO3光学参量振荡器

采用电光调Q脉冲Nd∶YAG激光的二次谐波 (5 32nm)抽运温度调谐的MgO∶LiNbO3晶体光学参量振荡器 ,调谐范围达 80 0nm～ 175 0nm。在单谐振运转条件下 ,抽运阈值为 2 1.5mJ/ pulse ,最大抽运能量为 5 8mJ时输出为 6 .45mJ ,在大信号情况下的能量转换效率达 11% ,输出线宽 1nm左右。     

超短中红外参量放大过程的时空走离特性

计算了MgO:LiNbO3晶体中,共线与非共线相位匹配光参量放大产生超短中红外激光脉冲过程中的相位匹配曲线、有效非线性系数以及时间和空间走离情况。结果表明,采用非共线相位匹配方式,可以实现三波间群速度匹配;在抑制了泵浦光与信号光之间的空间走离的同时加大了泵浦光与闲频光之间的空间走离,但这种影响可以忽略;同时非共线角的引入使相位匹配角增大,提高了有效非线性系数。因此,非共线角的引入在不影响空间走离的情况下,有效补偿超短中红外参量放大过程中的时间走离,有利于参量放大转换效率的提高。     

宽波段温度调谐MgO：LiNbO3光学参量振荡器

采用电光调Q脉冲Nd:YAG激光的二次谐波（532nm)抽运温度调谐的MgO:LiNbO3晶体光学参量振荡器,调谐范围达800nm-1750nm.在单谐振运转条件下,抽运阈值为21．5mJ/pulse,最大抽运能量为58mJ时输出为6．45mJ,在大信号情况下的能量转换效率达11％,输出线宽1nm左右。     

光纤激光泵浦MgO:PPLN高功率中波红外光参量振荡器

为实现高效率、高功率中波红外激光输出,研制基于MgO:PPLN晶体的中波红外光参量振荡器（OPO）,泵浦源为基于主振荡功率放大（MOPA）结构的线偏振掺Yb光纤激光器（YDFL）。实验结果表明:YDFL可实现最高79.1 W的1064.1 nm脉冲线偏振激光输出;在YDFL泵浦下,通过优化输出镜曲率半径和泵浦光束腰直径,该OPO实现最高9.15 W的3.754 μm脉冲激光输出,光光转换效率为11.57%,重复频率为300 kHz,脉冲宽度约为110 ns。     

KrF准分子激光的饱和参量与最佳激光输出

本文研究了在激光达到饱和强度下的上能级弛豫速率及泵浦速率两个参量与激光输出强度的关系。激光达到饱和强度时,上能级弛豫速率等于受激跃迁几率。根据这一特性,研究了Ar在4个大气压到6个大气压之间的四组N_(Ar)和N_(F_2),粒子数密度的Ar—Kr-F_2系统。计算了在给定激发速率和外耦合下的激光输出能量密度随Kr所占混合气体的比例而变化的关系。最后,从饱和强度下的上能级弛豫速率和泵浦速率得到了最大激光输出的条件,相应的激发速率、气压和气体混合的比例。     

高功率激光参量诊断技术研究

研究了如何准确测量惯性约束聚变实验中的激光能量和脉冲时间波形．从主光路上引出一束光，经衰减器后送入能量计，能量计放大器输出的模拟信号经归一化处理、A／D转换后输入8098单片机．数据采集完成后，再通过光耦合通信网和接口电路传输到中央控制室．通过超高速光电探测器把另一束激光转换为电脉冲信号，输入示波器，再经过GPIB总线接口和GPIB—LAN适配器AD007，使用虚拟仪器（VISA）语言经千兆以太网传输到中央控制室．对脉冲波形数据用小波滤波和自适应算法提取出脉冲时间波形参量．     

LD端面抽运Nd:YLF/KTA连续光参量振荡激光

采用非临界相位匹配切割,尺寸5mm×5mm×20mm的KTA作为非线性光学晶体,进行了基于半导体激光端面抽运Nd:YLF/KTA的内腔式连续光学参量振荡激光研究,获得了中红外3.5μm波段的连续激光输出。为了提高连续光参量振荡腔内信号光的功率密度,降低激光输出阈值,采用对信号光高反射的单谐振腔结构进行激光实验。在8.35W的抽运功率下,分别获得了335mW和110mW的3440nm和1505nm的激光输出,对应的总转换效率达到了5.6%。该实验研究表明半导体激光端面抽运的内腔式KTA连续光学参量振荡也能获得高效的中红外激光输出。     

失谐参量对激光不稳定性的影响

本文给出了在失谐情形下单模行波激光的五维激光方程组,并讨论了失谐参量对其不稳定性的影响。结果表明,在失谐情形下,第二阈值和临界自脉冲频率都随失谐参量的增大而增大。     

ps参量放大效应

本文报道用0.53μm波长超短脉冲序列泵浦角度调谐的LiNbO_3参量晶体,获得1%单程参量放大能量转换效率,并在0.8～1.6μm范围测得参量信号光和空载光波长调谐曲线.     

Fiber laser pumped burst-mode operated picosecond mid-infrared laser

We demonstrate a compact periodically poled MgO-doped lithium niobate(MgO:PPLN)-based optical parametric oscillator(OPO) quasi-synchronously pumped by a fiber laser system with burst-mode operation.The pump source is a peak-power-selectable pulse-multiplied picosecond Yb fiber laser.The chirped pulses from a figure of eight-cavity modelocked fiber laser seed are narrowed to a duration of less than 50 ps using an FBG reflector and a circulator.The narrowed pulses are directed to pass through a pulse multiplier and to form pulse bunches,each of which is composed of 13 subpulses.The obtained pulse bunches are amplified by two-stage fiber pre-amplifiers:one-stage is core-pumped and the other is cladding-pumped.A fiberized acousto-optic modulator is inserted to control the pulse repetition rate(PRR) of the pulse bunches before they are power-amplified in the final amplifier stage with a large mode area(LMA) PM Yb-doped fiber.The maximum average powers from the final amplifier are 85 W,60 W,and 45 W,respectively,corresponding to the PRR of2.72 MHz,1.36 MHz,and 0.68 MHz.The amplified pulses are directed to pump an MgO:PPLN-based optical parametric oscillator(OPO).A maximum peak power at 3.45 μm is obtained approximately to be 8.4 kW.Detailed performance characteristics are presented.     

High-energy picosecond single-pass multi-stage optical parametric generator and amplifier

We demonstrate a new management of multi-stage optical parametric generator(OPG)and amplifier(OPA)to obtain high-energy picosecond sources with high beam quality.The setup of multi-stage OPG-OPA requires mode-matching between the pump beam and the stable mode of the OPG-OPA.In a proof-of-principle experiment,the single-pass multi-stage OPG-OPA consists of three walk-off compensated KTP crystal pairs and two lenses,pumped by an 86 ps,1064 nm 10 kHz picosecond laser.The signal light at~1.77μm has an average output power of 502 mW with record energy up to 50.2μJ.The beam quality factor of the signal light can be improved toM²_x ×M²_yafter filtering out about 40%signal power.To the best of our knowledge,it is the first picosecond single-pass multi-stage OPG-OPA pumped at kHz regime.     

Amplification of fluorescence using collinear picosecond optical parametric amplification at degeneracy

We demonstrate the output characteristic of broadband parametric amplification of incoherent light pulses in a 355-nm pumped degenerate picosecond optical parametric amplification with either saturated or unsaturated amplification.The optical parametric amplifier is seeded by the fluorescence generated in a solution of pyridine-1 dye in ethanol.With the saturated amplification,we can obtain high energy incoherent light pulses,whose full width at half maximum bandwidth varies from 16 nm to 53 nm for the different phase matching angles near degeneracy.Moreover,the unsaturated bandwidth of the amplified pulses fits well to the calculated result at degeneracy.Selecting s-polarized fluorescence with a Glan-Taylor prism,the maximum bandwidth of the amplified fluorescence is found to be 59 nm for a purely s-polarized seed.The maximum output energy is 0.67 mJ for the optical parametric amplifier.By using an optical filter and compressor,the generated high energy incoherent light has great potential as the incoherent pump,signal or idler wave of a parametric down-conversion process,so that a wave with a high degree of coherence can be generated from an incoherent pump light.     

超短中红外参量放大过程的时空走离特性

 计算了MgO:LiNbO₃晶体中，共线与非共线相位匹配光参量放大产生超短中红外激光脉冲过程中的相位匹配曲线、有效非线性系数以及时间和空间走离情况。结果表明，采用非共线相位匹配方式，可以实现三波间群速度匹配；在抑制了泵浦光与信号光之间的空间走离的同时加大了泵浦光与闲频光之间的空间走离，但这种影响可以忽略；同时非共线角的引入使相位匹配角增大，提高了有效非线性系数。因此，非共线角的引入在不影响空间走离的情况下，有效补偿超短中红外参量放大过程中的时间走离，有利于参量放大转换效率的提高。     

Noncascading THz-wave parametric oscillator synchronously pumped by mode-locked picosecond Ti:sapphire laser in doubly-resonant external cavity

A noncascading terahertz (THz) wave parametric oscillator synchronously pumped by a mode-locked picosecond Ti:sapphire laser whose average power was less than 1 W was demonstrated with a noncollinear phase-matching MgO:LiNbO₃ crystal in an external enhancement cavity doubly resonant for both pump (780 nm) and signal (781-784 nm) waves. In the external cavity, in which the pump wave enhanced so as to reduce the pumping threshold of parametric processes, the signal wave could also resonate and thus be enhanced simultaneously, resulting in a THz wave output at approximately 0.9 THz as the idler wave. The novel dual enhancement of pump and signal waves reduced the threshold pumping intensity to approximately 50 MW/cm², which was much lower than that of a conventional externally pumped THz wave parametric oscillator with a crystal.     

Analysis of tunable picosecond pulse generation from a distributed feedback Ti：sapphire laser

A distributed feedback Ti:sapphire laser (DFTL) pumped by a 532nm Q-switched pulse is proposed for the generation of tunable picosecond pulses. With coupled rate equation model, the temporal characteristics of DFTL are obtained. The numerical solutions show that the DFTL pulse with a 50-ps pulse duration and as much as 3.SmJ pulse energy can be obtained under 40-m J, 5-ns pulse pumping. The dependence of output pulse width on the laser crystal‘s length, pumping pulse duration, and pumping rate is also discussed in detail.     

基于MgO:QPLN的多光参量振荡器电场调谐特性理论与实验研究

报道了基于掺氧化镁准周期极化铌酸锂(MgO:QPLN)的多光参量振荡器电场调谐特性理论与实验研究. 通过对电场调谐能力与极化结构参数间关联性的理论分析, 确定了高正负晶畴比MgO:QPLN电场调谐的可行性, 并模拟得到跨周期参量光输出波长与加载电压的关系曲线. 实验中通过对MgO:QPLN有效的电场加载, 实现了3.84 μm波段参量光的电场调谐, 频谱调谐带宽约6 nm, 调谐速率接近1 nm/kV, 进一步结合温度调谐, 实现了参量光宽谱段高精度的连续调谐. 所获得实验结果与理论模拟结果基本符合, 电场调谐在精度控制、快速响应方面相比于传统温度调谐更具技术优势.     

高增益LiNbO3光参量振荡器

报道一台采用调Q红宝石激光器泵浦的高增益角度调谐LiNbO_3光参量振荡器.最大输出能量和转换效率分别高达50mJ/pulse和19%.该振荡器从1.1444μm到1.7652μm连续可调谐.