Optically Detected Coherent Transients in Nuclear Hyperfine Levels

Using optical detection, we have observed rf nutation, free-induction decay, and echoes, on the 16.70-MHz nuclear hyperfine transition of dilute ${\mathrm{Pr}}^{3+}$ in La${\mathrm{F}}_3$ at 2 K. From a comparison of free-induction decay and echo decay we find that the previously observed linewidth of 200 kHz is inhomogeneous and that the homogeneous width is 19 kHz. On the basis of these measurements it is suggested that optical dephasing times for the ${}_{}{}^1{}_{}{}^{}D_2^{}{}_{}{}^{}\leftrightarrow {}_{}{}^3{}_{}{}^{}H_4^{}{}_{}{}^{}$ and ${}_{}{}^3{}_{}{}^{}P_0^{}{}_{}{}^{}\leftrightarrow {}_{}{}^3{}_{}{}^{}H_4^{}{}_{}{}^{}$ transitions are as long as ∼20 μ sec.