  A description is made of the process of excitation of coupled
longitudinal-transverse gravitational waves during the propagation of a strong
electromagnetic wave in a vacuum and when a standing electromagnetic wave
exists in the Fabry-Perot resonator. It is shown that such waves lead to the
appearance of transverse gravitational waves in empty space. It was established
that two standing high-frequency electromagnetic waves in a Fabry-Perot
resonator with close frequencies cause the appearance of a low-frequency
transverse gravitational wave in empty space.
