Optical free-induction decay of the F3+ center in NaF

We have measured the optical dephasing time T2 of the A11E1 zero-phonon transition of the F3+ color center in NaF by optical free-induction decay. In this way we eliminate the effect of the 54-GHz inhomogeneous broadening, and find a homogeneous linewidth of 20 5 MHz T2=164 nsec). We have also measured a spontaneous emission lifetime of T1=102 nsec. In the range 1.5-4 K, our results are consistent with the relation T2=2T1, indicating that optical dephasing is limited by population-decay processes. This relation was even more clearly demonstrated by performing the same experiment on the D lines of sodium vapor at 3 × 10-5 Torr, where the effects of collisions are negligible. We find that the dephasing is again limited by radiative decay, and that T2(323 nsec)=2T1(16.30.4 nsec). © 1978 The American Physical Society.