X-ray-boosted photoionization for the measurement of an intense laser pulse

Investigations show that the X-ray-boosted photoionization (XBP) has the following advantages for in-situ measurements of ultrahigh laser intensity I and field envelope F(t) (time t, pulse duration τ_L, carrier-envelope-phase φ): accuracy, dynamic ranges, and rapidness. The calculated XBP spectra resemble inversely proportional functions of the photoelectron momentum shift. The maximum momentum p and the observable value Q (defined as a double integration of a normalized photoelectron energy spectrum, PES) linearly depend on I^1/2 and τ_L, respectively. φ and F(t) can be determined from the PES cut-off energy and peak positions. The measurable laser intensity can be up to and over 10¹⁸ W/cm² by using high energy X-rays and highly charged inert gases.