理论研究了H+2分子发射高次谐波的空间分布情况。结果表明：分子谐波主要发生在两个H核附近。当核间距离较小时, 两个H核发射谐波强度几乎一致。核间距离增大,正向H核发射谐波强度大于负向H核。随着空间非均匀激光场的引入,H+2分子在较小核间距离时, 负向H核发射谐波强度略大于正向H核；在较大核间距离时,正向H核发射谐波强度大于负向H核。 随着空间非均匀激光场引入位置从负向移动到正向(－100 a.u.到100 a.u.),正向H核发射谐波强度逐渐减小。通过叠加谐波可获得脉宽在66 as和 62 as的超短阿秒脉冲。

The spatial distribution of high-order harmonic generation from H+2 molecules is theoretically investigated. Results show that the molecular harmonic emission mainly occurs around two H nuclei. When the internuclear distance is relatively small, the harmonic intensities of the two H nuclei are almost the same. The harmonic intensity emitted by the positive-H nucleus is higher than that of the negative-H nucleus with the internuclear distance increasing. With the introduction of the spatial inhomogeneous laser field, the harmonic intensity emitted by the negative-H nucleus is slightly higher than that of the positive-H nucleus when the internuclear distance of H+2 molecules is relatively small. The harmonic intensity emitted by the positive-H nucleus is higher than that of the negative-H nucleus when the internuclear distance is larger. As the spatial position of the space inhomogeneous laser field shifts from negative to positive(from －100 a.u. to 100 a.u.), the harmonic intensity emitted by the positive-H nucleus decreases gradually. The ultrashort attosecond pulses with durations of 66 as and 62 as can be obtained by superposition of harmonics.