Losses of tapered dielectric slab waveguides with axial variations in index of refraction

The effects of varying the index of refraction in the cladding along the length of a tapered dielectric waveguide are calculated using a local normal mode analysis. Variations in the length and shape of the taper are considered. The numerical results show that in some cases the losses can be reduced by an order of magnitude, even for short tapers whose length is of the order of the guide dimensions. The technique has several other potential applications, including waveguide bends, branches, and couplers.<
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