Nearly degenerate wave mixing and frequency up-conversion in coherent atomic media

Leonid A Bol'shov, N.N. Yolkin, Vladimir V. Likhanskii +1 more

Omar A. Ormachea, O. G. Romanov, Alexei L. Tolstik +3 more

One of the main advances of dynamical holography is the possibility to operate with coherent images in real-time experimental situation. Non-degenerate four-wave mixing has some advantages among different holographic methods because it gives the possibility to perform visualization of infra-red images or to convert visible radiation into ultra-violet region. In the work we study different schemes of frequency conversion of coherent images by thin and volume dynamic holograms nonlinearly formed in multilevel resonance media in conditions of non-degenerate four-wave mixing. The theoretical model of dynamic gratings formation in dye solutions based on coupled-wave equations has been developed. Experimental realization of frequency conversion of coherent images from infra-red to the visible and between different wavelengths of visible region has been performed. It has been shown that the criterion of hologram thickness is dependent on the optical density of medium and intensity of input radiation. The diffraction efficiency of dynamic gratings has been measured in conditions of optical bleaching and in the mode of strong absorption, enabling recording of thin gratings.

Ang Z

Phase conjugation of backward-and forward-wave produced by degenerate four-wave mixing using a nearly resonantly enhanced nonlinearity in four-level organic dye solutions was investigated. The conversion efficiency of 22% has been obtained in a 2.5×10-5-molar solution of chlorophyll A in methylalcohol with a 5mm interaction length and a pumping energy of ～8mj from SH of a Q-switched Nd:YAG. Degenerate four-wave mixing by two-photon resonant-enhancement in the solution of rhodamine 6G in alcohol was investigated. Measurements were performed which described the dependance of nonlinear reflectivities on the molar concentrations of the media and the intensities of the pumping and object waves. Phase conjugation characteristics of forward-wave in four-wave mixing process were theoretically analysed. Experiments have confirmed the theoretical prediction. The method of quartet degenerate four-wave mixing has been extended to the doublet degenerate casa. Using this method, image conversion from 1.06μm to 5320 A has been realized with a conversion efficiency of 25% in a 5 mm long saturable absorber made of organic dye 9740 solution in diehloroethane. Theoretical analysis shows that using a medium, which is a near resonant absorber for the infrared object wave but transparent for the visible reconstruction wave, the conversion efficiency may be well in excess of unity.

Richard C. Lind, Duncan G. Steel, Juan Francisco Lam +2 more

Binh Trong

Cunkai Wu, FAN JUN-YIN, Zhiying Wang

Phase conjugation of backward-and forward-wave produced by degenerate four-wave mixing using a nearly resonantly enhanced nonlinearity in four-level organic dye solutions was investigated. The conversion efficiency of 22% had been obtained in a 2.5 X 10-5 - molar solution of Chlorophyll A in methylalcohol with a 5 mm interaction length and a pumping energy of ～ 8 mJ from SH of a Q-switched Nd: YAG. Degene-rate four-wave mixing by two-photon resonant-enhancement in the solution of rhodamine 6G in alcohol was studied. Measurements were performed which described the dependence of nonlinear reflectivities on the molar concentrations of the media and the intensities of the pumping and object waves. Phase conjugation characteristics of forward-wave in four-wave mixing process were theoretically analysed. Experiments have cofirmed the theoretical prediction. The method of quartet degenerate four-wave mixing had been ex-tended to the doublet degenerate case. Using this method image conversion from 1.06 μm to 5320 ? had been realized with a conversion efficiency of 25% in a 5 mm long satu-rable absorber made of organic dye 9740 solution in dichloroethane. Theoretical analy-sis showed that using a medium, which is a near resonant absorber for the infrared object wave but is transparent for the visible reconstruction wave, the conversion efficiency may be well in excess of unity.