We use an interferometic scheme to extract the phase distribution of the electron wave packet from above-threshold ionization in elliptically polarized laser fields. In this scheme, an electron wave packet released from a circularly polarized laser pulse acts as a reference wave and interferes with the electron wave packet ionized by a time-delayed counter-rotating elliptically polarized laser field. The generated vortex-shaped interference pattern in the photoelectron momentum distribution enables us to extract the phase distribution of the electron wave packet in the elliptically polarized laser pulse with high precision. By artificially screening the ionic potential at different ranges when solving the time-dependent Schördinger equation, we find that the angle-dependent phase distribution of the electron wave packet in the elliptically polarized laser field shows an obvious angular shift as compared to the strong-field approximation, whose value is the same as the attoclock shift. We also show that the amplitude of the angle-dependent phase distribution is sensitive to the ellipticity of the laser pulse, providing an alternative way to precisely calibrate the laser ellipticity in the attoclock measurement.

我们使用干涉法从椭圆偏振激光场中的阈值以上电离中提取电子波包的相位分布。在该方案中，从圆偏振激光脉冲释放的电子波包用作参考波，并且与被时延反向旋转椭圆偏振激光场电离的电子波包干扰。在光电子动量分布中产生的涡旋形干涉图样使我们能够高精度地提取椭圆偏振激光脉冲中电子波包的相位分布。在求解与时间有关的Schördinger方程时，通过人工筛选不同范围的离子电势，我们发现，与强场近似相比，椭圆偏振激光场中电子波包的角度相关相位分布表现出明显的角位移，强场近似的值与原子钟位移相同。我们还表明，与角度相关的相位分布的幅度对激光脉冲的椭圆率很敏感，从而提供了另一种方法来精确校准原子钟测量中的激光椭圆率。