Linear and nonlinear crystal optics using the magnetic field of light

We study the $^{7}F_{0}\ensuremath{\rightarrow}^{5}D_{1}$ magnetic-dipole transition in the $4f$ shell of europium ions at a wavelength of 527.5 nm and demonstrate spectral hole burning, ion class selection, and optical pumping to specific ground hyperfine states. We then use the narrow lines of the selected ions to observe linear group delay of a weak probe pulse with a group velocity of $c/3800$. We also demonstrate electromagnetically induced transparency by establishing a $\mathrm{\ensuremath{\Lambda}}$ scheme between the ground hyperfine levels and driving the ions to a dark state.