What are Exciting in Laser Science

ＷｈａｔａｒｅＥｘｃｉｔｉｎｇｉｎＬａｓｅｒＳｃｉｅｎｃｅＹｕｅｎ－ＲｏｎＳｈｅｎＤｅｐａｒｔｍｅｎｔｏｆＰｈｙｓｉｃｓ,ＵｎｉｖｅｒｓｉｔｙｏｆＣａｌｉｆｏｒｎｉａＭａｔｅｒｉａｌｓＳｃｉｅｎｃｅｓＤｉｖｉｓｉｏｎＬａｗｒｅｎｃｅＢｅｒｋｅｌｅｙＮ...     

强激光场中脉冲激发的连续拉曼光谱理论

在强场中发展了时间相关的光谱理论，提出了一个有很好性质的近似，籍此长脉冲激发体系的计算将变得非常容易，讨论了强场下的连续拉曼光谱，发现产生类荧光散射的入射频率范围比弱场大。     

Sub-10 fs laser pulses with repetition rate of 1.1 GHz by a Ti: sapphire oscillator

We demonstrate a compact Ti： sapphire oscillator with ring cavity configuration. By optimizing the intra-cavity dispersion with chirped mirrors, pulses with repetition rate of 1.1 GHz are coupled out by the uncoated wedges in the cavity. Under 7W CW pump laser centered at 532 nm, the average power of the output pulses is about 30 mW, the duration is less than lOfs and the spectrum spans from 670 nm to 920 nm.     

飞秒Z—scan法测量有机溶液的双光子吸收截面

按照单光束Z—scan法,利用飞秒激光脉冲对Rb甲醇溶液进行了测量研究,详细研究了光强大小对实验结果的影响,通过对样品池和溶剂进行Z扫描,排除了样品池和溶剂发生非线性吸收带来的误差,利用薄样品理论对测量数据进行计算处理,所得结果与其他方法测得的结果相吻合,证明了此实验方法对有机溶液的测量和处理方法的合理性和有效性．     

Modulation of synchronous calcium oscillations in hippocampal neurons by photostimulation of astrocytes with femtosecond laser

A large body of evidence indicates that astrocytes play an important role in a range of brain functions through calcium (Ca²⁺) signaling. Experimentally evoking Ca²⁺ signaling is a useful technique for investigating the functions of astrocytes. However, conventional stimulation methods typically have poor spatio-temporal precision, and some are invasive. Our group has developed a technique to overcome these problems, in which astrocytes are photostimulated with a femtosecond laser. In the current study, we applied this method to a hippocampal neural network to explore astrocytic functions in detail. The results revealed that applying photostimulation to astrocytes in a cultured hippocampal astrocyte-neuron network caused the following changes: (i) Synchronous Ca²⁺ oscillations in neurons were induced; (ii) spontaneous Ca²⁺ synchrony instantaneously emerged; and (iii) high-frequency spontaneous Ca²⁺ synchrony was regulated. Thus, astrocytic Ca²⁺ signaling evoked by photostimulation was found to modulate synchronous Ca²⁺ oscillations in hippocampal neurons. We propose that photostimulation with a femtosecond laser will serve as a powerful tool in investigating astrocytic functions at the network level.     

飞秒激光中超热电子束的传输特性

为了探索超热电子束的传输特性,利用光学CCD相机在靶背法线方向测量了光学渡越辐射(OTR)积分成像图案.实验在100 TW掺钛蓝宝石激光器上进行,飞秒激光与固体靶作用后,靶表面发光信号由空间分辨装置聚焦成像并引到CCD狭缝上.在厚度为100μm的Ta靶背表面观测到渡越辐射(TR)光斑呈现较平滑的圆形结构,而且中心亮度高于周围,这显然包含了非相干与相干渡越辐射的成分,与理论模拟结果比较接近;在复合靶10μm Ta+20μm Cu+1μm Ta背表面观测到TR光斑虽然也呈现大致的圆形结构,但光斑极不均匀,中间有很明显的光斑分裂,大约有两个分离的光斑出现.所有这些现象反映了超热电子束的传输特性.     

飞秒电脉冲光电导自相关探测

飞秒激光脉冲光电导取样技术在超短电脉冲的产生与测量及其在超高速光电子器件特性研究、光通信与光电信息处理等方面有着十分诱人的应用前景,已成为近年来超快光电子学研究的热点[1,2].本文介绍采用飞秒激光脉冲自相关方法在低温生长砷化镓(ＬＴＧａＡｓ)共面微带传输线?..     

飞秒激光和大功率激光的发展与应用

综述了激光技术的新发展和研究的热点,重点论述了飞秒激光技术的最新发展和它在生命科学、基因工程、信息科学、超微细加工及物理学等领域中的应用以及大功率激光技术的发展和它在国防军事领域中的应用。     

飞秒激光强场条件下碘化钠分子解离过程的理论研究

我们采用了精确的量子力学方法对飞秒激光强场条件下碘化钠分子的解离过程进行了理论研究.从计算结果中我们可以得到两个结论：第一,当泵浦-探测延迟时间超过300飞秒的时候,碘化钠分子开始光解离;第二,随着延迟时间的增加,有越来越多的处于激发态上的碘化钠分子被光解离.