Abstract
We measured the dependence of high-order harmonic generation (HHG) on the angle α between polarization directions of high-intensity femtosecond laser pulses in the pump and probe experiment. The experimental results of N2 and O2 are compared with the calculated ones using the theory developed recently to illustrate the characteristic properties of HHG from aligned N2 and O2, and then the excellent agreement is obtained. It is also shown that the observed α-dependent harmonic signal is strongly influenced by the degree of alignment of molecules and is not identical to the harmonic distribution calculated as a function of the angle between the field direction and the molecular axis.
