Efficient Generation of Coherent Soft X-Ray Radiation

WPCD 2 B V P Z快递10cpi？X，k x 6X@8；X@HP LaserJet系列II HPLase II PrS x@，T0OPX@#|x2B 9224520 Milchberg强皮秒和亚皮秒脉冲与中等密度稀有气体的非线性相互作用产生相干真空紫外光和软X射线辐射是一个极具实用和基本意义的领域。我们建议进行实验，以解决该领域中出现的一些问题，并从开发更有效的相干、软X射线辐射源的答案出发。(I)将利用双色实验研究强激光场使原子共振位移对高次谐波产生效率的影响：用较长的(100ps)红外脉冲来移动能级，以及用可变延迟的亚皮秒可见脉冲来产生谐波。(2)将使用单色和双色泵浦探测技术来确定离子在产生谐波中所起的作用。(Iii)将使用6.7米真空紫外光谱仪对高次谐波(由长脉冲和短脉冲产生)进行高精度光谱分析。(4)将研究涉及两个驱动波长的多波混频，以实现有效的相位匹配和接近共振的条件。这有望极大地提高短波长发电的效率。(V)我们最近在强短激光脉冲光学导引方面取得的成功也将被用来确定导光结构对谐波产生效率的影响。***

WPCD 2 B V P Z Courier 10cpi ? x x x , k x 6 X @ 8 ; X @ HP LaserJet Series II HPLASEII.PRS x @ , t 0 OpX @ #| x 2 B 9224520 Milchberg The generation of coherent vacuum ultraviolet and soft X ray radiation by the nonlinear interaction of intense picosecond and subpicosecond pulses with moderate density rare gases is an area of great practical and fundamental interest. We propose experiments to address a number of questions that have arisen in the field and to proceed from the answers to the development of more efficient sources of coherent, soft X ray radiation. (i) The effect of shifting of atomic resonances by an intense laser field on the high harmonic generation efficiency will be investigated using a two color experiment: a longer (100 ps), infrared pulse to shift the levels, and a variably delayed subpicosecond visible pulse to generate harmonics. (ii) The role played by ions in generating harmonics will be determined using both one and two color pump probe techniques. (iii) High precision spectroscopy of the high harmonics (generated with both long and short pulses) will be performed with a 6.7 m VUV spectrometer. (iv) Multiwave mixing involving two driving wavelengths will be studied to achieve efficient phase matching and near resonant conditions. This is expected to dramatically increase the efficiency of short wavelength generation. (v) Our recently achieved success in optical guiding of intense short laser pulses will also be exploited to determine the effect of guiding structures on harmonic generation efficiency. ***