Аннотация:The formation of a single-cycle light bullet during the propagation of a femtosecond laser pulse with an arbitrary initial ellipticity of the polarization of the light field of the mid-infrared range in lithium fluoride is studiedfor the first time experimentally and numerically. It is found that the degree of ellipticity of polarization determines the effect of the absolute phase of the carrier frequency on the nonlinear optical interaction of the light bullet with the medium. The transition from the linear to circular polarization is accompanied by the disappearance of modulation of the density of color centers induced in lithium fluoride by the single-cyclelight bullet. This occurs because the amplitude of the strength vector of the light field with the circular polarization always coincides with the maximum of the pulse envelope and the effect of “breathing” of the light bullet in the isotropic medium is fundamentally absent.