Observation of coherent and incoherent terms of the Specular Inverse F
araday Effect (SIFE) in YBa2Cu3O7-delta is reported. The spectroscopic
potential of measurements of the coherent and incoherent terms of SIF
E is revealed and two components of nonresonant cubic susceptibility t
ensor in this superconducting material are measured and found to be in
10(-9)-10(-8)esu range.