Terahertz emission dependence on the intensity ratio of 400–800 nm in generating terahertz waves from two-color laser-induced gas plasma

A transient photocurrent model is used to explain terahertz emission from gas plasma irradiated by a laser pulse and the second harmonic. By introducing the second harmonic, 400 nm, the corresponding terahertz emission is greatly enhanced. The exact dependence of terahertz emission on the intensity ratio of 400–800 nm is studied for the case with total intensity of 5.00 × 1014 W/cm2. Results show the emission reaches the maximum at about the case for energy distribution of Iω = 4.00 × 1014 W/cm2, I2ω = 1.00 × 1014 W/cm2.

► A transient photocurrent model is used to explain terahertz emission from gas plasma irradiated by two-color laser pulses, with one the second harmonic of the other.
► By introducing the second harmonic 400 nm, the corresponding terahertz emission is greatly enhanced.
► The exact dependence of terahertz emission on the intensity ratio of 400–800 nm is studied here.