Nonlinear ionization of atomic gases by intense bichromatic laser fields can be used for efficient generation of coherent electromagnetic radiation in the terahertz(THz) frequency domain [1,2].The physics underlying this method reduces to the presence of left-right(with respect to the polarization direction) asymmetry in photoelectron momentum distributions generated by a coherent superposition of two quasimonochromatic laser pulses of different carrier frequencies.