New type of guided waves in birefringent media

The existence of waves guided by thin dielectric films deposited over a positive birefringent crystal for waveguide parameters below usual cutoff is discussed. This additional kind of guided wave has a hybrid nature and occurs in properly tailored waveguides when a suitable orientation of the crystal optical axis, relative to the waveguide axis, is taken. The dependence of the allowed orientations on various waveguide parameters has been analyzed. Noticeable fast variations, with potential interest for switching applications, have been found.<
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