Fresnel and wide-angle equation analyses of microlenses

The applicability of the Fresnel and wide-angle formalisms to glass microlenses is analyzed. For a representative, small, one-dimensional microlens formed from a single-mode slab waveguide, paraxial and wide-angle techniques are in relatively good agreement despite the large refractive index differences at the glass-air interface. Furthermore, in a test case, a single value of n/sub 0/ could be used in the Fresnel equation for electric field propagation through the microlens, while n/sub 0/=1 should be used outside the lens, greatly simplifying the programming and calculational effort. While this conclusion is not expected to be universally valid, it should apply to many standard components in integrated optics. The accuracy of the wide-angle technique relative to other often-cited procedures is established.<>