physica status solidi (b)
Coherent four‐photon spectroscopy of two‐photon eesonances of trivalent rare‐earth ions
L. A. Yuguryan, A. G. Makhanek
Abstract
Abstract Using wave functions which are transformed in irreducible representations of corresponding point groups of symmetry, an analysis is carried out of the tensor structure of resonance cubic susceptibility. Polarization characteristics are found of a four‐photon parametric process in the conditions of two‐photon resonance between the components of fine structure of trivalent rare‐earth ions in crystals. The number of independent and nonzero tensor components of resonance cubic susceptibility is determined and their number is shown to be much smaller than it follows from the general features of the crystal symmetry. The signs of resonance cubic susceptibility are calculated for concrete two‐photon transitions.