Theoretical scheme for simultaneously observing forward-backward photoelectron holography.

Photoelectron angular momentum distribution of He⁺ driven by a few-cycle laser is investigated numerically. We simultaneously observe two dominant interference patterns with one shot of lasers by solving the 3D time-dependent Schrodinger equation. Analysis of a semiclassical model identifies these two interference patterns as two types of photoelectron holography. The interference pattern with P_z>0 is a type of forward rescattering holography, which comes from the interference between direct (reference) and rescattered (signal) forward electrons ionized in the same quarter-cycle. The interference pattern with P_z<0 is a type of backward rescattering holography, which comes from the interference between a direct electron ionized in the third quarter-cycle and rescattered backward electron ionized in the first quarter-cycle. Moreover, we propose a method to distinguish this backward rescattering holography and intracycle interference patterns of direct electrons.