We report on optically induced optical switching of a 632.8-nm signal
in a Nd3+-doped, two-mode finer based on a nonlinearity resonantly enh
anced by the dopant. A fast, 0.38-mus component was observed in the sw
itched signal, which we believe is due to cross relaxation between clu
stered ions. We demonstrated a 600-kHz switch in a 1.14-m elliptical-c
ore fiber with 0.31 muJ of launched 807-nm pump energy. Information ab
out cluster size and speed of the cross-relaxation process is inferred
from the switch dynamics.