Excited-state absorption in the lasing wavelength region of alexandrite

The excited-state absorption cross section
\sigma_{2a}(E)
in the gain wavelength region of alexandrite has been determined and is shown to limit the vibronic laser range at both high and low energy. The maximum in vibronic laser emission is due to a minimum in
\sigma_{2a}(E)
near 13 000 cm
^-1
.
\sigma_{2a}(E)
is less than 10
^-20
cm
²
between 12 000 and 14 000 cm
^-1
.