Peculiarities of the phase grating recording in polymer films containing 4-keto Bacteriorhodopsin are investigated under absorption saturation. The phase-modulated beams technique is used to measure photoresponse from the films in real time. Three maxima of the photoresponse are detected: The two first (at ∼ 1 and ∼ 10 s) correspond to the positive amplitude of the phase grating, whereas the third OE to the negative one (at ∼ 1 min.). The phenomenon is explained, as theoretical analysis shows, by the spatial distortions of the grating, resulting in the fundamental spatial harmonic sign exchange. These maxima, we believe, correspond to three photocycles in the 4-keto Bacteriorhodopsin molecule, for which a novel scheme is suggested. The results of theoretical simulations are shown to be in good agreement with the experiment.
© 1999 Optical Society of AmericaPDF Article