Entirely electromagnetic analysis of microlenses without a beam-shaping aperture

We suggest an approach for numerically studying the performance of cylindrical microlenses without a beam-shaping aperture based on the boundary-element method (BEM). We divide the infinite microlens boundary into two components: The first part is an infinite expanded flat interface excluding the curved interface, and the second part is only the originally curved microlens interface. The resulting transmitted field can be regarded as the composition of two fields: One is generated by the first boundary, and the other is contributed from the second boundary. We carry out numerical simulations for two microlens systems, with or without aperture. We find that, for the nonapertured system, an ideal focusing feature is still observed; however, the axial distribution of the transmitted field exhibits an oscillation, different from the apertured system. It is expected that the current approach may provide a useful technique for the analysis of micro-optical elements.