Mode transformations in terms of the constituent Hermite-Gaussian or Laguerre-Gaussian modes and the variable-phase mode converter

Recently the passage of light beams through mode-order-preserving optical e lements has been described in terms of the constituent Hermite-Gaussian mod es [L. Alien et al., Phys. Rev. E 60 (1999) 7497]. When described instead i n terms of the constituent Laguerre-Gaussian modes, interesting parallels b etween the two formulations emerge. These parallels are employed to constru ct a variable-phase mode converter. (C) 2000 Elsevier Science B.V. All righ ts reserved.