  We study the effects of a possible strong final state interaction among
longitudinal W's in gamma.gamma --> W+W-. The relevant partial wave amplitudes
are modified by an Omn\`es function approximated by a Breit-Wigner form factor.
We study the fractional cross section f_{00} = \sigma_{LL}/\sigma_{Total} with
both W's longitudinally polarised, in the presence of a J = 2 resonance (M =
2.5 TeV, Width = 500 GeV) or a J = 0 resonance (M = 1 TeV, Width = 1 TeV),
whose parameters are scaled up from the f_2 and \sigma resonances in the \pi\pi
system. We also examine the effects of final state interaction in the case of
polarised photons (J_z = 0 or J_z = 2), and the impact on the
Drell-Hearn-Gerasimov sum rule.
