  We investigate the sensitivity of future photon-photon colliders to low scale
gravity scenarios via the process $\gamma\gamma \to ZZ$ where the Kaluza-Klein
boson exchange contributes only when the initial state photons have opposite
helicity. We contrast this with the situation for the process $\gamma \gamma
\to \gamma \gamma$ where the $t$ and $u$ channel also contribute. We include
the one-loop Standard Model background whose interference with the graviton
exchange determines the experimental reach in measuring any deviation from the
Standard Model expectations and explore how polarization can be exploited to
enhance the signal over background. We find that a 1 TeV linear collider has an
experimental reach to mass scale of about 4 TeV in this channel.
