Abstract

The interest in χ⁽²⁾-materials and related nonlinear wave-propagation effects has been driven for a long time by potential applications in efficient blue-light generation by Second Harmonic Generation (SHG) and electro-optical switching.¹ Recently additional interest has been raised by advances in polymeric χ⁽²⁾-materials which promise large nonlinear phase-shifts by cascading of second order effects.² From a practical point of view the interest in SHG has been dominated by guided mode—guided mode interactions. Guided mode—radiation mode interactions have been studied as well³ but analytical relations are difficult to obtain due to the problems associated with normalisation of radiation modes and consequently most work has focused on efficiency of SHG in the no-depletion limit. However, coupling to radiation modes and accompanying depletion of the field at ω can be easily studied by means of the SHG Beam Propagation Method.⁴ This method is an extension of normal BPM's and consists of a split-step approach in which the calculation of the propagation of the fields at the two wavelengths is alternated by the calculation of the nonlinear interactions.

© 1995 IEEE