量子阱激光二极管泵浦Nd:YLF固体激光器的调Q

用国产脉冲功率200mW的多量子阱激光二极管列阵(MQW-LDA)泵浦Nd:YLF固体激光器,实现了声光调Q。得到激光的脉宽70ns,能量1μJ,重复频率100Hz。波形起伏小于1％。     

High power diode-laser-pumped twisted-mode Nd:YAG laser

We describe the design and performance of a high power diode-laser-pumped twisted-mode Nd:YAG laser. Using four high power 1 W diode lasers as pumping, nearly single frequency output power of 950 mW was obtained. Stable single frequency operation was realized with the help of injection locking with a master monolithic ring diode-laser-pumped Nd:YAG laser     

CW laser operation of Nd:YLF

CW laser operation of Nd:YLF is reported for the first time and, in a comparison to Nd:YAG, exhibits a lower threshold and higher single-mode average power. The TEM00mode volume of Nd: YLF was observed to be a factor of four larger than Nd:YAG, resulting in twice the TEM00mode average power. This result is attributed to the substantially lower thermal lensing of YLF with respect to YAG. In comparative measurements the stimulated emission cross section of Nd:YLF was found to be1.8 times 10^{-19}cm²for the π oscillation and1.2 times 10^{-19}cm²for the σ oscillation, as compared to2.4 times 10^{-19}cm²for Nd:YAG. The spectroscopic and lasing parameters of Nd:YLF indicate a potential for this material in high peak and average powerQ-switched applications.     

Resonant passive mode-locked Nd:YLF laser

The authors review the theory of resonant passive mode locking (RPM) lasers and present experimental results for an improved Nd:YLF RPM laser that produced stable pulses as short as 3.7 ps at a repetition rate of 250 MHz. The average output power was 550 mW with 1.3-W average pump power from a Ti:sapphire laser. It was possible to couple 85% out of the nonlinear coupled cavity and still maintain stable mode locking. In RPM and amplitude nonlinearity such as absorption bleaching in a semiconductor reflector introduces an intensity-dependent reflectivity which strongly mode locks the laser. The reduced carrier lifetime in a low-temperature MBE-grown (LT) InGaAs-GaAs quantum-well reflector produces a sufficiently fast saturable absorber in the coupled cavity     

量子阱激光二极管泵浦单块Nd∶YLF激光器

用多量子阱激光二极管列阵(MQW-LDA)泵浦单块Nd:YLF激光器,脉冲工作,获得1.047μm的线偏光输出。阈值泵浦功率6.8mW,斜率效率为24％,输出脉冲能量达6.7μJ;用增益开关获得50mW的峰值功率输出。理论计算了泵浦阈值、斜率效率,获得了增益开关的数值解结果,与实验基本一致。     

Simultaneous Q-switching and mode-locking in a diode-pumped Nd:YVO4-Cr4+:YAG laser

Parametric studies of passive Q-switching and mode-locking in a Nd ³⁺:YVO₄-Cr⁴⁺:YAG laser were theoretically carried out. Simultaneous mode-locking and Q-switching was also experimentally studied. It was found that over 90% of the output power could be mode-locked in a diode-pumped passively Q-switched Nd³⁺:YVO₄-Cr⁴⁺:YAG laser. The average pulse duration of the mode-locked pulse train was estimated to he around 110~150 ps. The highest peak power of a single pulse near the maximum of the Q-switched envelope was greater than 100 kW     

LD端泵Nd:YAG SESAM锁模激光器的研究

本文分析了SESAM锁模与染料可饱和吸收体锁模的区别,提出了SESAM锁模机理的初步模型。根据对腔参数的分析结果,进行了一系列实验,实现了半导体端泵Nd:YAG激光器的SESAM锁模运转,这是首次利用直腔进行SESAM锁模,为进一步研究SESAM锁模奠定了基础。     

GaAs被动调Q固体激光特性研究

使用紧凑的直线平-凹腔结构,利用半导体饱和吸收片GaAs实现了二极管(LD)端面抽运Nd:GdVO4高重复频率的被动调Q 1.06μm激光运转,在8 W的泵浦功率下获得平均输出功率达0.98 W的稳定激光输出,最小脉冲宽度为60 ns.最高重复频率达240 kHz.     

1047 nm laser diode master oscillator Nd:YLF power amplifier laser system

A master oscillator power amplifier (MOPA) laser transmitter system at 1047 nm wavelength using a semiconductor laser diode and a diode pumped solid state (Nd:YLF) laser (DPSSL) amplifier is described. A small signal gain of 23 dB, a near diffraction limited beam, l Gbit/s modulation rates and >0.6 W average power are achieved. This MOPA laser has the advantage of amplifying the modulation signal from the laser diode master oscillator (MO) with no signal degradation.<>     

Energy-transfer upconversion and thermal lensing in high-powerend-pumped Nd:YLF laser crystals

Thermal lensing in an end-pumped Nd:LiYF₄ rod, under lasing and nonlasing conditions, has been investigated. Under lasing conditions, a weak thermal lens, with dioptric power varying linearly with pump power, was observed. Under nonlasing conditions, where higher inversion densities were involved, hence relevant to Q-switched operation or operation as an amplifier, a much stronger thermal lens was measured, whose power increased nonlinearly with pump power. This difference has been attributed to the increased heat deposition due to the subsequent multiphonon decay following various interionic upconversion processes, which increase strongly under nonlasing conditions, and is further exacerbated by the unfavorable temperature dependencies of heat conductivity and the rate of change of the refractive index with temperature. A strategy for reducing upconversion and its associated thermal loading, without degrading laser performance, is discussed     

GaAs对脉冲Nd:YAG激光器的调Q和锁模

本文分析半导体材料GaAs对1064nm激光的可饱和吸收特性,在闪光灯抽运的平凹腔和平凸腔Nd:YAG激光器中,插入GaAs样品作为调Q器件,实现了激光器的被动调Q运转,分别获得脉冲宽度32.7ns(平凹腔)和30.9ns(平凸腔)的激光脉冲。实验上研究了平凹腔腔长和输出镜透过率对调Q激光输出性能的影响。当平凹腔腔长增加到125cm时,观察到GaAs对1064nm激光的被动锁模。对上述实验结果给予了合理的理论解释。     

Nd:YLF激光放大器实验研究

描述了LD阵列侧面泵浦Nd：YLF激光放大器的实验研究,采用LD阵列紧密围绕棒状Nd：YLF直接泵浦,这种结构不但提高泵浦光利用率,而且具有很好的泵浦均匀性。该激光放大器的口径为φ3mm,在1053nm小信号增益为2．84。     

Magnified expansion and compression of subpicosecond pulses from afrequency-doubled Nd:YLF laser

Pulses from a mode-locked frequency-doubled Nd:YLF laser have been spectrally broadened and subsequently expanded to more than 200 ps and recompressed to 750 fs by grating compressors with magnifying telescopes. The design magnifies the time delay dispersion to a factor 10 times larger than achievable with standard compressors of similar size. The design of the system and its sensitivity to the variations in the position of its optical components is analyzed. The scheme allows efficient amplification of subpicosecond pulses in dye amplifiers     

Actively initiated quasi-passive mode-locking in a CW SELFOC Nd:glass laser

Actively initiated quasi-passive mode-locking has been achieved in a small-power CW SELFOC Nd:glass laser. Three means have been taken to enhance the pulse intensity incident on a saturable dye to a magnitude sufficient for nonlinear absorption initiation: 1) tight focusing, 2) controlled spiking oscillation, and 3) auxiliary active mode-locking. Mode-locked pulses having an 11-12-ps pulsewidth were obtained. Interpretation concerning the observed mode-locked-pulse intensity-correlation curves is presented. To obtain satellite-pulse-free mode-locked pulses, a modified mode-locking process with sufficiently long buildup time is considered.     

Quantitative pump-induced wavefront distortions in laser-diode- andflashlamp-pumped Nd:YLF laser rods

Detailed interferometric measurements of the induced thermal distortions due to laser-diode and xenon flashlamp pumping of Nd:LiYF ₄ are presented. The thermal distortions are quantified in terms of the primary aberrations of defocus, astigmatism, coma, and spherical. Defocus and astigmatism are shown to dominate the thermal aberrations. The measured defocus and astigmatism are converted to the conventional thermal-focal lengths in two perpendicular directions with respect to the Nd:YLF crystalline c axis for each of the two polarization states σ and π. A comparison of the thermal-focal lengths measured with our xenon flashlamp and laser-diode-pumped rods is given when the rods are pumped to the same small signal gain. We calculate effective dioptric-power coefficients from our data for comparison to those reported in the literature for krypton-flashlamp pumping. A thermal time constant of 1.5 s is measured for our laser-diode-pumped Nd:YLF laser rod     

Mode-locked operation of a Nd:YLF laser and amplification in aQ-switched Nd:glass slab laser

A Nd:YLF laser pumped with a CW dye laser and acoustooptically mode locked at 38 MHz has an output power of 130 mW and a pulse length of 60 ps. Insertion of intracavity etalons and misaligning the mode locker allows for stable operation with a continuous range of pulse lengths from 60 ps to 4 ns. The 1.053-μm emission permits amplification of these pulses in a Q-switched Nd:phosphate glass slab laser oscillator up to intensities limited by optical damage     

Energy transfer up-conversion and excited state absorption of laserradiation in Nd:YLF laser crystals

Experiments at room temperature were carried out to study the higher order processes that produced the yellow and blue fluorescence observed in Nd:YLF laser crystals, which were pumped by lasers with wavelengths between 785 nm and 811 nm, and with the pump power density ranging from 10 to 30 kW/cm², or the stored energy density, 15-45 J/cm³. The analysis of the experimental results provided an explanation for the performance degradation of a Q-switched laser with increasing pump intensity. These higher order processes were energy transfer up-conversion and excited state absorption of both pump and laser radiation. A model was also developed based upon rate equations to describe these higher order processes. This model allowed us to discriminate between these processes and to determine which one played the most important role. The experimental results agreed well with the predictions of the model. It is concluded that the energy transfer up-conversion process is the dominant mechanism for the population of the ⁴G_7/2 multiplet. It is also concluded that excited state absorption of the 1.05 μm or 1.3 μm radiation from the ⁴G_7/2 multiplet play a significant role in populating the ²P_3/2, ² D(1)_5/2, and ²P_½ manifolds, and in the performance of Nd:YLF lasers operating in the pulsed mode. The effect of excited state absorption of the pump radiation from the ⁴F_½ multiplet is much less important     

Very high gain Nd:YLF amplifiers

High-gain Nd:YLF rod amplifiers in which single-pass, small signal gains of over 1700 have been obtained along with stored energy densities ⩾0.4 J/cm² are discussed. The ability of Nd:YLF amplifiers to support such gains is a result of high parasitic oscillation thresholds, due primarily to the low refractive index of the material. These results suggest that Nd:YLF is an excellent candidate for amplifiers where high specific stored energies and/or very high gains are required     

全固态高功率连续单频稳频1053-nmNd:YLF激光器

报道了激光二极管(LD)端面抽运的1053 nm全固态连续单频稳频Nd:YLF环形激光器的设计及实验结果.为克服Nd:YLF晶体应力裂纹极限小的缺点,采用了较长的、低掺杂的沿c轴切割的Nd:YLF晶体.激光器的阈值抽运功率为4.7 W,当抽运光功率为17.9 W时,单频输出功率可达4.21 W,长期功率稳定性为±0.8%(4.75 h),自由运转频率波动为±10 MHz/min.为了改善激光器的频率稳定性,利用电子伺服系统将激光器的频率锁定在共焦法布里-珀罗(F-P)腔的共振透射峰上,锁定后,激光器的频率波动降低为±1.7 MHz/min.     

连续Nd∶YAG稳频倍频激光器

在连续稳频Nd:YAG激光器的基础上,重新设计了腔形,使用角度匹配的KTP和MgO:LiNbO_3晶体倍频。在输入功率为2.5kW时,获得基频光800mW输出,强度波动小于2％,频率稳定性优于2MHz。同时获得50～100mW的倍频光输出,强度波动小于5％,频率稳定性优于5MHz。