  We theoretically study the generation of terahertz (THz) radiation by
two-color filamentation of ultrashort laser pulses with different wavelengths.
We consider wavelengths in the range from 0.6 to 10.6 $\mu$m, thus covering the
whole range of existing and future powerful laser sources in the near, mid and
far-infrared. We show how different parameters of two-color filaments and
generated THz pulses depend on the laser wavelength. We demonstrate that there
is an optimal laser wavelength for two-color filamentation that provides the
highest THz conversion efficiency and results in generation of extremely
intense single cycle THz fields.
