STUDY OF THE RETRACING BEHAVIOR OF THE PHASE-MATCHING ANGLE IN 2ND-HARMONIC GENERATION

The retracing behavior of the phase-matching angle (RBPA) in many nonl inear optical crystals for second harmonic generation (SHG) has been d emonstrated by calculation. The generality of this phenomenon is succe ssfully explained by a theoretical analysis bawd on classical optics. The wavelengths of the fundamental waves and phase-matching angles for describing the RBPA of eight kinds of crystals are presented. Further more, we point out that RBPA exists generally in both uniaxial and bia xial crystals for both type I and type II SHG.