Phase conjugation, imaging in biological media and characterization of quantum noise by parametric image amplification

We review recent results about parametric image amplification obtained in o ur group and in others. First, forward phase conjugation has been used to r estore images through aberrant media and to image objects embedded through thick biological tissues. Second, quantum noise in image amplification has been actively studied by several groups, leading to theoretical demonstrati on of image entanglement and squeezing, as well as experiments on noiseless image amplification and characterization of the correlations in the spatia l fluctuations of amplified images. (C) 2000 Academie des sciences/Editions scientifiques et medicales Elsevier SAS.