Generation of isolated attosecond pulses by the harmonic spectrum of MgO under a three-color laser pulse

Based on the numerical solution of the semiconductor Bloch equation, we study the high-order harmonic radiation behavior of MgO crystals driven by combined pulses. 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 about 370 as. This study provides a new perspective for all-solid-state compact optical devices.