Hernández-García C, Holgado W, Plaja L, Alonso B, Silva F, Miranda M, Crespo H, Sola I J
Opt Express. 2015 Aug 10;23(16):21497-508. doi: 10.1364/OE.23.021497.
We present evidence for self-stabilization of the relative spectral phase of high-order harmonic emission against intensity variations of the driving field. Our results demonstrate that, near the laser focus, phase matching of the harmonic field from a macroscopic target can compensate for the intensity dependence of the intrinsic phase of the harmonics emitted by a single radiator. As a consequence, we show experimentally and theoretically the insensitivity of the harmonic spectra produced at the laser focus against variations of the carrier-envelope phase (CEP) of a sub-two-cycle driving field. In addition, the associated attosecond pulse trains exhibit phase locking against CEP changes of the few-cycle driver.
我们给出了高次谐波发射的相对光谱相位相对于驱动场强度变化的自稳定证据。我们的结果表明，在激光焦点附近，来自宏观靶的谐波场的相位匹配可以补偿单个辐射体发射的谐波的固有相位对强度的依赖性。因此，我们通过实验和理论证明了在激光焦点处产生的谐波光谱对亚两周期驱动场的载波包络相位（CEP）变化不敏感。此外，相关的阿秒脉冲序列对几周期驱动源的CEP变化表现出锁相特性。
