利用分裂算符法求解速度规范下的含时薛定谔方程,研究了一维氦原子处于单色红外场、红外场与紫外场形成的双色组合场中产生的高次谐波谱,分析了在截止位置附近高次谐波的转换效率与激光波长(800-2000 nm)的关系,发现在双色组合场驱动下截止位置附近高次谐波的转换效率随波长的变化为η(λ)∝λ-x,其中的数值取决于激光场的强度,但是只要选取合适场强的组合场就能提高截止位置附近高次谐波的转换效率.%By solving the time-dependent Schr(o)dinger equation under velocity gauge with split-operator method, we studied the high harmonics of one-dimensional helium atom exposed to one-color laser field and two-color fields composed of IR field and UV field. And the relationship between conversion efficiency of high-order harmonic generation near the cut-off position and wavelength of the laser ( 800-2000 nm) was also analyzed. It was found that high-order harmonic conversion efficiency driven by two-color laser field near the cut-off position changes with wavelength as η( λ ) ∝ λ -x, where the x value depends on the intensity of laser field, and the appropriate selection of intensity of combined laser field can improve high harmonic conversion efficiency near the cut-off position.
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