[en] We study the helicity amplitudes of the process γγ→ZZ in the standard model at high energy. These amplitudes receive contributions from the W and charged quark and lepton loops, analogous to those encountered in the γγ→γγ, γZ cases studied before. But γγ→ZZ also receives contributions from the Higgs s-channel poles involving the effective Higgs-γγ vertex. At energies g∝300 GeV, the amplitudes in all three processes are mainly helicity-conserving and almost purely imaginary; which renders them a very useful tool in searching for new physics. As an example, a SUSY case is studied, and the signatures due to the virtual effects induced by a chargino-, charged slepton- or a lightest stop-loop in γγ→ZZ, are explored. These signatures, combined with the analogous ones in γγ→γγ and γγ→γZ, should help identifying the nature of possible new physics particles. (orig.)