The thesis focuses on processes occurring due to the interaction of matter with strong laser fields, especially with two-color fields. An extension to phase-of-the-phase spectroscopy is introduced with two particular applications demonstrated. Next, optimization of the laser radiation conversion to THz frequencies is addressed. The superiority of using two-color circularly polarized corotating fields of mid-IR wavelengths is theoretically predicted. Finally, a method of analyzing the numerically obtained photoelectron spectra with respect to the registration time of electrons is proposed.<eng>
