Charged Higgs production at photon colliders in 2HDM-III
  We study charged Higgs production in the process $\gamma\gamma\to A^0\to W^- H^+$. The processes $\gamma\gamma\to A^0$ are loop mediated in a 2HDM. This is due to the fact that photons only couple directly to charged particles and the Higgs only couples to particles with mass acquired via Higgs mechanism. Although in MSSM the contribution from the process $\gamma\gamma\to A^0$ is too small, it has been found that in a more general 2HDM it could be enhanced. On the other hand, the boson $A^0$ can decay in $W^- H^+$ at tree level and the charged Higgs can decay in fermions. So, the whole process under study is $\gamma\gamma\to A^0\to (W^-\to l\nu) (H^+\to f_if_j)$ in 2HDM-III. Evidence about charged Higgs existence could demonstrate that structure of the Higgs sector has several multiplets. 
R. Martinez, J.-Alexis Rodriguez and S. Sanchez