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 elements has been described in terms of the constituent Hermite-Gaussian modes [L. Alien et al., Phys. Rev. E 60 (1999) 7497]. When described instead in terms of the constituent Laguerre-Gaussian modes, interesting parallels between the two formulations emerge. These parallels are employed to construct a variable-phase mode converter. (C) 2000 Elsevier Science B.V. All rights reserved.