Using Stark-pulse-modulated photon echoes, we observe a novel type of
rephasing phenomenon in a Eu3+- and Pr3+-codoped Y2SiO5 crystal. By ad
justing the Stark pulse during the rephasing and dephasing periods one
can observe a full recovery of the photon echo, corresponding to perf
ect dephasing-rephasing balancing of the perturbations. We propose to
use this effect as a spectroscopic technique to distinguish between re
versible and irreversible Stark interactions. (C) 1997 Optical Society
of America