Photoionization hole burning and nonlinear Zeeman effect in CaF_2:Sm^2+

Persistent spectral hole burning has been observed in CaF(2):Sm(2+) and originates from photoionization of the Sm(2+) ion. This represents a new class of persistent hole-burning materials. We have used hole burning to measure the nonlinear Zeeman effect of the (7)F(0)A(1g) ? A(1u) transition at 695.8 nm with a resolution of ~100 MHz. We find a nonlinear coefficient of 0.93 Hz/G(2), which is close to the value of 1.0 Hz/G(2) calculated for the (7)F(0)-(7)F(1) interaction. This shows that the dominant contribution to the nonlinear Zeeman effect comes from the ground state.