Generation peculiarities of the second harmonics laser radiation at synchronism angles close to 90°

The problem of the second harmonic generation in uniaxial crystals at angles of synchronism close to 90° is considered at the approximation of an assumed field. It is shown that this important special case is characterized by a number of distinctive peculiarities, which were not discussed earlier and, more importantly, contradict the commonly held ideas of physics of the considered process. © 2011, Pleiades Publishing, Ltd.