Constraints on doubly charged Higgs interactions at linear collider

Production of a single doubly charged Higgs boson Δ−− in polarized e+e− and e+γ collision modes of the linear collider have been investigated. The mass range of Δ−− to be probed extends up to the collision energy. The diagonal lepton number violating Yukawa coupling hee will be tested at least three orders of magnitude more strictly than in present experiments.