Optical Gating With Asymmetric Field Ratios for Isolated Attosecond Pulse Generation

A technique to improve double optical gating for generating isolated attosecond pulses is introduced. In this method, the ratio between the amplitudes of the counter-rotating pulses is altered to decrease the field strength prior to the linearly-polarized gate cycle. The result is a decrease in the preionization of the gas target used for generating high-order harmonics. In addition to improving phase matching and increasing the saturation intensity, this development also allows isolated attosecond pulse production with longer driving laser pulses.