Use of undoped crystals of the yttrium/aluminum/borate family for creating non-linear effects

x1-x334Crystals of the yttrium/aluminium/borate family are used for producing UV light. To produce UV light with the described crystal family a crystal of the family AMX(BO), wherein both A and also M stand for an element from the group Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, A≠M and X is selected from the group consisting of Al, Ga, Sc and 0≦x≦1, is used as a non-linear optical element to produce light of a wavelength of less than 0.450 μm.