2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/49747The T-reversal-violating optical gyrotropy is discussed. A new optical phenomenon of photon polarization plane rotation in a medium exposed to an electric field caused by the Stark mixing of atom (molecule) levels and T-odd phenomenon of photon polarization plane rotation appearing at photon passing through non-center-symmetrical diffraction grating are considered. The experimental methods to observe these phenomena are proposed.Latex, 30 pages with 10 Postscript figures, added references and figuresHigh Energy Physics - Phenomenologytext