When RF radiation is applied to a sample exhibiting transient spectral
hole burning, the RF field can cause a Zeeman modulation of the wavel
ength of the spectral hole. The transmitted laser light involved in th
e hole burning becomes modulated. An analysis of the signal amplitude
is used to obtain a measure of the Zeeman splittings. The technique is
illustrated for an optical transition in a tetragonal centre in CaF2:
Ho3+.