Interference modulation of photoemission from biased metal cathodes driven by two lasers of the same frequency

We propose to use two lasers of the same frequency to achieve interference modulation of photoelectron emission. Using a quantum mechanical model, we study the time-resolved photoelectron energy spectra and emission current modulation under different laser and dc fields. We find that strong interference modulation of photoemission can be easily achieved with two lasers of the same frequency, due to, on one hand, the straightforward access to the single-frequency laser pairs in experiments and, on the other hand, the low threshold value of the ratio of the laser fields for large modulation depth even with a strong dc field. Our study demonstrates the capability of using interference modulation by single-frequency laser pairs for practical measurements of time-resolved photoelectron energy spectra.