Generation of Ultrashort Light Bullets in Dispersive Kerr Media Using the Fourth—Order Dispersion—Dependent Spatiotemporal Instability

A new method for generation of a train of ultrashort pulses or a sequence of ultrashort light bullets is proposed. This method is based on the fourth-order dispersion-dependent spatiotemporal instability in dispersive Kerr media. The repetition-rate of the generated bullets can be made quite large by increasing the corresponding spatial modulation frequency locating in the new instability region resulted from fourth-order dispersion.     

类氖锗X光激光双程放大实验研究

本文在神光装置上,进行了类氖锗X光激光双程放大实验研究.实验中使用了硅/钼多层膜X光平面反射镜.用平场光栅谱仪测量了X光激光的时间积分和时间分辨信号.实验证实了X光激光的双程放大.时间积分结果表明,双程放大为单程放大信号的5倍多;时间分辨结果表明,对多层镜的作用时间作修正后,双程放大信号的增强倍数还要大.在本实验条件下,多层镜的寿命约为400—700ps.     

会聚厄米-双曲余弦高斯光束的光强分布和焦移

 基于厄米-双曲余弦高斯光束通过无光阑限制薄透镜聚焦的解析传输公式，研究了厄米-双曲余弦高斯光束聚焦区域的光强分布，并对光束的焦移进行了分析，讨论了偏心参数对光强主极大位置的影响。结果表明：TEM₁₁模厄米-双曲余弦高斯光束的相对焦移（绝对值）随偏心参数和菲涅尔数的减小而增大，菲涅尔数较大时相对焦移趋于零。TEM₂₂模光束在偏心参数小于0.54时，轴外与轴上光强极大值的比值大于1，此时光强主极大在轴外，偏心参数大于0.54时则相反；在偏心参数等于0.54时比值为1，此时光束有两个主极大，偏心参数愈大光强愈集中于轴上。使用LW法和GH法得到的TEM₂₂模光束的相对焦移（绝对值）随偏心参数和菲涅尔数的变化规律与TEM₁₁模光束一致，但相同参数下使用这两种方法得出的具体结果不同。     

激光核聚变与高功率激光:历史与进展

回顾激光聚变近50年来的发展历程,评述聚变物理与高功率激光驱动器的研究进展,展望聚变能源未来前景.     

A Phase-Controlled Optical Parametric Amplifier Pumped by Two Phase-Distorted Laser Beams

We theoretically study the phase characteristic of optical parametric amplification （OPA） or chirped pulse OPA （OPCPA） pumped by two phase-distorted laser beams. In the two-beam-pumped optical parametric amplification （TBOPA）, due to spatial walk-off, both of the pump phase distortions will be partly transferred to signal in a single crystal so as to degrade the signal beam-quality, which will be more serious in high-energy OPCPA. An OPA configuration with a walkoff-compensated crystal pair is demonstrated for reducing the signal phase distortion experienced in the first stage and ensuring the signal phase independent of two pump phase distortions through the second crystal, hence maintaining the signal beam-quality. Such a TBOPA is similar to the conventional quantum laser amplifier by means of eliminating its sensitivity to the phase and number of the pump beams.     

Widely tunable dual-pump parametric amplifiers with photonic crystal fibres

This paper theoretically studies the double-pumped fibre-optical parametric amplifiers （FOPAs） in photonic crystal fibres. Two distinct working regimes of FOPAs are researched, which depend on the dispersion at the central wavelength of the two pumps. Extremely broad tuning range can be obtained when the central pump wavelength is in the normal dispersion regime and is insensitive to the wavelength separation between the two pumps, while the tuning range is narrow in the anomalous dispersion regime and can be significantly enhanced by increasing the wavelength separation. Impacts of higher-order dispersions and temporal walk-off on the gain spectra are also discussed.     

激光表面纹理化过程中的Rayleigh-Taylor不稳定性

用表面纹理化的热模型 ,分析了固体表面的熔化和重固化的物理过程 ,计算了在纹理化过程中的表面温度、穿透深度、熔化深度、相面移动速度等物理量 ,提出了 Rayleigh-Taylor不稳定性形成周期化结构的机理。     

Terahertz-wave generation by surface-emitted four-wave mixing in optical fiber

We propose a novel terahertz-wave source through the four-wave mixing effect in a conventional single-mode optical fiber pumped by a dual-wavelength laser whose difference frequency lies in the terahertz range. Surface-emitted geometry is employed to decrease absorption loss. A detailed derivation of the terahertz-wave power expression is presented using the coupled-wave theory. This is a promising way for realizing a reasonable narrow-band terahertz-wave source.     

高功率钕玻璃激光放大器优化设计的研究现状与展望

系统地分析了高功率钕玻璃光放大器及其优化设计的研究现况和进一步发展的方向，简要报道了在钕玻璃放大器优化设计方面所取得的主要成果。