Polarization rotation effects associated with the two-photon transition of Γ 1-excitonic molecules in CuCl

Abstract

Two-photon polarization rotation effects have been observed around the two-photon resonance of the Γ 1 -excitonic molecule, EM, in CuCl. It has been found that the effects originate from the rotation of the polarization plane of a linearly polarized weak probe beam induced by the irradiation of a strong circularly polarized excitation beam when the sum of the energies of both beams resonates to the EM level at 6.3722 eV. The effects have been observed in a wide range over 10 meV around the EM resonance. The observation of the effects offers a sensitive method to detect the modulation in the complex refractive index due to the two-photon transition of the EM's. It is also pointed out that compact optically-controlled fast-switching devices are assured by making use of these effects.