Generation of Isolated Attosecond Pulses by the Harmonic Spectrum of MgO under a Three-Color Laser Pulse

This study examines the high-order harmonic radiation behavior of MgO crystals driven by combined pulses based on the numerical solution of the semiconductor Bloch equation. We found that compared with the monochromatic pulse, the MgO crystal can radiate a continuous harmonic spectrum with two platforms driven by the three-color combined pulse. The reason is that under the three-color combined pulse, the electron ionization and recombination can be effectively controlled within a half-optical cycle of the laser pulse. Using this continuous spectrum, we synthesized an isolated attosecond pulse with a duration of approximately 370 as. This study provides a new perspective on all-solid-state compact optical devices.